<PAGE>   1
     As filed with the Securities and Exchange Commission on June 1, 2000.

                                                    Registration No. 333-_______

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             Registration Statement
                        Under the Securities Act of 1933

                               F.N.B. CORPORATION
             (Exact name of registrant as specified in its charter)

         PENNSYLVANIA                                        25-1255406
(State of other jurisdiction                                 (I.R.S. Employer
of incorporation or organization)                            Identification No.)

         ONE F.N.B. BOULEVARD
         HERMITAGE, PA                                       16148
         (Address of Principal                               (zip code)
         Executive Offices)

                         F.N.B. CORPORATION 401(k) PLAN
                              (Full Title of Plan)
                             ---------------------

                                PETER MORTENSEN
                      CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                               F.N.B. CORPORATION
                              ONE F.N.B. BOULEVARD
                              HERMITAGE, PA 16148
                    (Name and address of agent for service)

                                 (412) 981-6000
         (Telephone number, including area code, of agent for service)
                              -------------------

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=========================================================================================================================
                                                   Proposed maximum       Proposed maximum
 Title of securities to        Amount to be       offering price per     aggregate offering        Amount of
      be registered             registered               share                  price          registration fee
-------------------------------------------------------------------------------------------------------------------------
<S>                            <C>                <C>                    <C>                   <C>
 Common stock, par value         300,000              $18.69 (2)             $5,607,000            $1,480.25
     $2.00 per share
=========================================================================================================================
</TABLE>


(1) There are also being registered hereunder such number of additional shares
of Common Stock which may become available for purchase in accordance with the
provisions of the Plan in the event of any change in the outstanding shares of
F.N.B. Corporation, including a stock dividend or stock split.

(2) Estimated solely for the purposes of calculating the registration fee:
Calculated pursuant to Rule 457(c) based upon the market value per share of
F.N.B. Corporation common stock as of May 26, 2000.


<PAGE>   2


                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents filed by F.N.B. Corporation ("FNB" or the
"Corporation") with the Securities and Exchange Commission (the "Commission")
are incorporated by reference into this Registration Statement:

                           1. FNB's Annual Report on Form 10-K for the fiscal
                  year ended December 31, 1999.

                           2. FNB's definitive Proxy Statement filed with the
                  Commission pursuant to Section 14 of the Securities Exchange
                  Act of 1934, as amended, (the "Exchange Act"), in connection
                  with the Annual Meeting of Shareholders of FNB held on April
                  17, 2000.

                           3. The description of FNB's Common Stock, par value
                  $2.00 per share (the "Common Stock"), contained in FNB's
                  Registration Statement filed under Section 12 of the Exchange
                  Act, including all amendments and reports updating such
                  description.

                  The consolidated financial statements of FNB at December 31,
1999 and 1998, and for each of the three years in the period ended December 31,
1999, have been audited by Ernst & Young LLP, independent auditors, as set forth
in their report thereon, incorporated by reference in FNB's Annual Report on
Form 10-K dated March 13, 2000, and incorporated herein by reference. As to
1998, their report is based, in part, on the report of Bobbitt, Pittenger &
Company, P.A., independent auditors, who audited Guaranty Bank & Trust Company.
As to 1997, their report is based, in part, on the reports of Hacker, Johnson,
Cohen & Grieb PA, independent auditors, who audited Seminole Bank and Citizens
Holding Corporation and Bobbitt, Pittenger & Company, P.A., independent
auditors, who audited Guaranty Bank & Trust Company. The financial statements
referred to above are included in reliance upon such reports given on the
authority of said firms as experts in accounting and auditing.

                  All documents subsequently filed by FNB with the Commission
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the
date of this Registration Statement, but prior to the filing of a post-effective
amendment to this Registration Statement which indicates that all securities
offered by this Registration Statement have been sold or which deregisters all
such securities then remaining unsold, shall be deemed to be incorporated by
reference into this Registration Statement. Each document incorporated by
reference into this Registration Statement shall be deemed to be a part of this
Registration Statement from the date of the filing of such document with the
Commission until the information contained therein is superseded or updated by
any subsequently filed document which is incorporated by reference into this
Registration Statement or by any document which constitutes part of the
prospectus relating to the F.N.B. Corporation 401(k) Plan meeting the
requirements of Section 10(a) of the Securities Act of 1933, as amended (the
"Securities Act").

ITEM 4. DESCRIPTION OF SECURITIES.

                  The class of securities to be offered under the Registration
Statement is registered under Section 12 of the Exchange Act.


<PAGE>   3


ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

                  The legality of the securities offered hereby will be passed
upon by Cohen & Grigsby, P.C., Pittsburgh, Pennsylvania, counsel to FNB.

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

                  The effect of charter, by-law, statutory and other provisions
whereby the directors and officers of FNB may be insured or indemnified against
liability as officers and directors are set out below:

                  Numbered Paragraph 6.b. of the Articles of Incorporation, as
amended, of FNB provides as follows:

                  Directors and Officers of the Corporation shall be indemnified
        as of right to the fullest extent now or hereafter permitted by law in
        connection with any actual or threatened action, suit or proceedings,
        civil, criminal, administrative, investigative or other (whether brought
        by or in the right of the Corporation or otherwise), arising out of
        their service to the Corporation or to another organization at the
        request of the Corporation, or because of their positions with the
        Corporation. Persons who are not Directors or Officers of the
        Corporation may be similarly indemnified in respect of such service to
        the extent authorized at any time by the Board of Directors of the
        Corporation. The Corporation may purchase and maintain insurance to
        protect itself and any such Director, Officer or other person against
        any liability, cost or expense asserted against or incurred by him in
        respect of such service, whether or not the Corporation would have the
        power to indemnify him against such liability by law or under the
        provisions of this paragraph. The provisions of this paragraph shall be
        applicable to persons who have ceased to be Directors or Officers, and
        shall inure to the benefit of the heirs, executors and administrators of
        persons entitled to indemnity hereunder.

                  Article IX of the Bylaws of the Corporation provides that the
Corporation shall indemnify each director and officer of the Corporation and of
its controlled subsidiaries made or threatened to be made a party to any civil,
criminal, administrative or investigative action, suit or proceeding (whether
brought by or in the name of the Corporation or otherwise) arising out of such
director's or officer's service to the Corporation or to another organization at
the Corporation's request against all expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement actually and reasonably incurred
by such director and officer in connection with such action, suit or proceeding.
Indemnification shall not be made with respect to actions, suits or proceedings
where the act or omission giving rise to the claim for indemnification has been
determined to have constituted willful misconduct or recklessness or where
prohibited by law. In addition, expenses incurred by each director and officer
in defending any such action, suit or proceeding, shall be paid by the
Corporation in advance of the final disposition of such action, suit or
proceeding if an undertaking (in form and scope satisfactory to the Corporation)
shall have been furnished to the Corporation to repay amounts so advanced if and
to the extent it shall ultimately be determined that such officer or director is
not entitled to indemnification and certain other conditions shall have been
satisfied. The Corporation may purchase and maintain insurance, create a fund of
any nature, grant a security interest or otherwise secure or insure in any
manner its indemnification obligations.

                  Section 1741 of the Pennsylvania Business Corporation Law
provides that a corporation shall (subject to the provisions described in the
second succeeding paragraph) have the power to indemnify any person who was or
is a party, or is threatened to be made a party, to any threatened, pending or
completed action or proceeding, whether civil, criminal, administrative or
investigative (other than an action by or in the right of the corporation), by
reason of the fact that such person is or was a representative of the
corporation, or is or was serving at the request of the corporation as a
representative



                                      -2-
<PAGE>   4


of another domestic or foreign corporation for profit or not-for-profit,
partnership, joint venture, trust or other enterprise, against expenses
(including attorneys' fees), judgments, fines and amounts paid in settlement
actually and reasonably incurred by such person in connection with the action or
proceeding if such person acted in good faith and in a manner he reasonably
believed to be in, or not opposed to, the best interests of the corporation and,
with respect to any criminal proceeding, had no reasonable cause to believe his
conduct was unlawful. The termination of any action or proceeding by judgment,
order, settlement or conviction, or upon a plea of nolo contendere or its
equivalent shall not of itself create a presumption that such person did not act
in good faith and in a manner which he reasonably believed to be in, or not
opposed to, the best interests of the corporation and, with respect to any
criminal proceeding, had reasonable cause to believe that his conduct was
unlawful.

                  Section 1742 of the Pennsylvania Business Corporation Law
provides that a corporation shall (subject to the provisions described in the
succeeding paragraph) have the power to indemnify any person who was or is a
party, or is threatened to be made a party, to any threatened, pending or
completed action by or in the right of the corporation to procure a judgment in
its favor by reason of the fact that such person is or was a representative of
the corporation, or is or was serving at the request of the corporation as a
representative of another domestic or foreign corporation for profit or
not-for-profit, partnership, joint venture, trust or other enterprise against
expenses (including attorneys' fees) actually and reasonably incurred by such
person in connection with the defense or settlement of the action if such person
acted in good faith and in a manner he reasonably believed to be in, or not
opposed to, the best interests of the corporation. Indemnification shall not be
made in respect of any claim, issue or matter as to which such person has been
adjudged to be liable to the corporation unless and only to the extent that the
court of common pleas of the county in which the registered office of the
corporation is located or the court in which the action was brought determines
upon application that, despite the adjudication of liability but in view of all
the circumstances of the case, such person is fairly and reasonably entitled to
indemnity for such expenses that the court of common pleas or other court deems
proper.

                  Under Section 1744 of the Pennsylvania Business Corporation
Law, any such indemnification (unless ordered by a court) shall be made by the
corporation only as authorized in the specific case upon a determination that
indemnification of the representative is proper in the circumstances because
such person has met the applicable standard of conduct. Such determination shall
be made:

                  (1) By the Board of Directors by a majority vote of a quorum
         consisting of directors who were not parties to the action or
         proceeding; or

                  (2) If such quorum is not obtainable or, even if obtainable a
         majority vote of a quorum of disinterested directors so directs, by
         independent legal counsel in a written opinion; or

                  (3) By the shareholders.

                  Notwithstanding the above, Section 1743 provides that to the
extent that a representative of the corporation has been successful on the
merits or otherwise in defense of any action or proceeding referred to above, or
in defense of any claim, issue or matter therein, such person shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred by such person in connection therewith.

                  Under Section 1745 of the Pennsylvania Business Corporation
Law, expenses (including attorneys' fees) incurred in defending any action or
proceeding may be paid by the corporation in advance of the final disposition of
the action or proceeding upon receipt of an undertaking by or on behalf of the
representative to repay such amount if it is ultimately determined that such
person is not entitled to be indemnified by the corporation.



                                      -3-
<PAGE>   5


                  Section 1746 of the Pennsylvania Business Corporation Law
further provides that the indemnification provided by Sections 1741, 1742 and
1743 and the advancement of expenses provided by Section 1745 shall not be
deemed exclusive of any other rights to which a person seeking indemnification
or advancement of expenses may be entitled under any bylaw, agreement, vote of
shareholders, disinterested directors or otherwise, both as to action in his
official capacity and as to action in another capacity while holding that
office. A corporation may create a fund of any nature, which may, but need not
be, under the control of a trustee, or otherwise secure or insure in any manner
its indemnification obligations, whether arising under or pursuant to Section
1746 or otherwise. Indemnification pursuant to Section 1746 shall not be made in
any case where the act or failure to act giving rise to the claim for
indemnification is determined by a court to have constituted willful misconduct
or recklessness.

                  Indemnification pursuant to Section 1746 under any bylaw,
agreement, vote of shareholders, or directors or otherwise may be granted for
any action taken or any failure to take any action and may be made whether or
not the corporation would have the power to indemnify the person under any other
provision of law except as provided in such Section 1746 and whether or not the
indemnified liability arises or arose from any threatened, pending or completed
action by or in the right of the corporation. Section 1746 declares such
indemnification to be consistent with the public policy of Pennsylvania.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

                  Not applicable.

ITEM 8. EXHIBITS.

                  4.1               F.N.B. Corporation 401(k) Plan (incorporated
                                    by reference to Exhibit 4.1 of the
                                    Corporation's Registration Statement on Form
                                    S-8, filed August 13, 1992, File Number
                                    33-50780).

                  5.1               Opinion of Cohen & Grigsby, P.C. regarding
                                    legality of the securities being registered.

                  23.1              Consent of Ernst & Young LLP.

                  23.2              Consent of Bobbitt Pittinger & Company, P.A.

                  23.3              Consent of Hacker, Johnson, Cohen & Grieb PA

                  23.4              Consent of Cohen & Grigsby, P.C., included
                                    in opinion filed as Exhibit 5.1.

                  24                Power of Attorney

ITEM 9. UNDERTAKINGS.

(a)               Rule 415 Offering undertaking:

                  The undersigned registrant hereby undertakes:

                  (1) To file, during any period in which offers or sales are
being made, a post-effective amendment to this registration statement:



                                      -4-
<PAGE>   6


                       (i)      To include any prospectus required by Section
                                10(a)(3) of the Securities Act of 1933;

                       (ii)     To reflect in the prospectus any facts or events
                                arising after the effective date of the
                                registration statement (or the most recent
                                post-effective amendment thereof) which,
                                individually or in the aggregate, represents a
                                fundamental change in the information set forth
                                in the registration statement;

                       (iii)    To include any material information with respect
                                to the plan of distribution not previously
                                disclosed in the registration statement or any
                                material change to such information in the
                                registration statement;

provided, however, that paragraphs (a)(l)(i) and (a)(l)(ii) do not apply if the
registration statement is on Form S-3 or Form S-8 and the information required
to be included in a post-effective amendment by those paragraphs is contained in
periodic reports filed by the registrants pursuant to Section 13 or Section
15(d) of the Securities Exchange Act of 1934 that are incorporated by reference
in the registration statement.

                  (2) That, for the purpose of determining any liability under
the Securities Act of 1933, each post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

(b)               Filings Incorporating Subsequent Exchange Act Documents by
                  Reference undertaking:

                  The undersigned registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act of 1933, each
filing of the registrant's annual report pursuant to Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing
of an employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

(c)               Filing of Registration Statement on Form S-8 undertaking:

                  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the registrant of expenses
incurred or paid by a director, officer or controlling person of the registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.





                                      -5-
<PAGE>   7


                                   SIGNATURES

                  The Registrant. Pursuant to the requirements of the Securities
Act of 1933, the registrant certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form S-8 and has duly caused
this registration statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Hermitage, Commonwealth of
Pennsylvania, on May 31, 2000.

                                          F.N.B. CORPORATION


                                          By /s/ Peter Mortensen
                                             -----------------------------------
                                             Peter Mortensen, Chairman and Chief
                                             Executive Officer

                  Pursuant to the requirements of the Securities Act of 1933,
this registration statement has been signed by the following persons in the
capacities and on the dates indicated.


<TABLE>
<S>                                      <C>                                    <C>
/s/ Peter Mortensen                      Chairman, Chief Executive Officer      May 31, 2000
---------------------------------        and Director (Principal Executive
Peter Mortensen                          Officer)

/s/ Stephen J. Gurgovits                 Vice Chairman and Director             May 31, 2000
---------------------------------
Stephen J. Gurgovits

/s/ Gary L. Tice                         President, Chief Operating Officer     May 31, 2000
---------------------------------        and Director
Gary L. Tice

/s/ John D. Waters                       Vice President and Chief Financial     May 31, 2000
---------------------------------        Officer (Principal Accounting
John D. Waters                           Officer)

                                         Director                               May 31, 2000
---------------------------------
W. Richard Blackwood

                                         Director                               May 31, 2000
---------------------------------
Alan C. Bomstein
</TABLE>



                                      -6-
<PAGE>   8
<TABLE>
<S>                                      <C>                                    <C>
/s/ William B. Campbell                  Director                               May 31, 2000
---------------------------------
William B. Campbell

/s/ Charles T. Cricks                    Director                               May 31, 2000
---------------------------------
Charles T. Cricks

/s/ Henry M. Ekker                       Director                               May 31, 2000
---------------------------------
Henry M. Ekker

/s/ James S. Lindsay                     Director                               May 31, 2000
---------------------------------
James S. Lindsay

/s/ Paul P. Lynch                        Director                               May 31, 2000
---------------------------------
Paul P. Lynch

                                         Director                               May 31, 2000
---------------------------------
Edward J. Mace

                                         Director                               May 31, 2000
---------------------------------
Robert S. Moss

                                         Director                               May 31, 2000
---------------------------------
William A. Quinn

/s/ William J. Strimbu                   Director                               May 31, 2000
---------------------------------
William J. Strimbu

/s/ Archie O. Wallace                    Director                               May 31, 2000
---------------------------------
Archie O. Wallace

/s/ James T. Weller                      Director                               May 31, 2000
---------------------------------
James T. Weller

                                         Director                               May 31, 2000
---------------------------------
Eric J. Werner

                                         Director                               May 31, 2000
---------------------------------
Benjamin Wiley

                                         Director                               May 31, 2000
---------------------------------
Donna C. Winner
</TABLE>







                                      -7-
<PAGE>   9


                                  EXHIBIT INDEX



                  4.1               F.N.B. Corporation 401(k) Plan (incorporated
                                    by reference to Exhibit 4.1 of the
                                    Corporation's Registration Statement on Form
                                    S-8, filed August 13, 1992, File Number
                                    33-50780.

                  5.1               Opinion of Cohen & Grigsby, P.C. regarding
                                    legality of the securities being registered.

                  23.1              Consent of Ernst & Young LLP.

                  23.2              Consent of Bobbitt Pittinger & Company, P.A.

                  23.3              Consent of Hacker, Johnson, Cohen & Grieb PA

                  23.4              Consent of Cohen & Grigsby, P.C., included
                                    in opinion filed as Exhibit 5.1.

                  24                Power of Attorney
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "F.N.B. CORPORATION FORM S-8", "secsgml_size_bytes": 27896}]
{"company-data": {"conformed-name": "FNB CORP/PA", "cik": "0000037808", "assigned-sic": "6021", "irs-number": "251255406", "state-of-incorporation": "PA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-38372", "film-number": "647984"}, "business-address": {"street1": "ONE FNB BLVD", "street2": "HERMITAGE SQUARE", "city": "HERMITAGE", "state": "PA", "zip": "16148", "phone": "7249816000"}, "mail-address": {"street1": "HERMITAGE SQUARE", "city": "HERMITAGE", "state": "PA", "zip": "16148"}, "former-company": {"former-conformed-name": "CITIZENS BUDGET CO", "date-changed": "19750909"}}
1
     As filed with the Securities and Exchange Commission on June 1, 2000.

                                                    Registration No. 333-_______

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             Registration Statement
                        Under the Securities Act of 1933

                               F.N.B. CORPORATION
             (Exact name of registrant as specified in its charter)

         PENNSYLVANIA                                        25-1255406
(State of other jurisdiction                                 (I.R.S. Employer
of incorporation or organization)                            Identification No.)

         ONE F.N.B. BOULEVARD
         HERMITAGE, PA                                       16148
         (Address of Principal                               (zip code)
         Executive Offices)

                         F.N.B. CORPORATION 401(k) PLAN
                              (Full Title of Plan)
                             ---------------------

                                PETER MORTENSEN
                      CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                               F.N.B. CORPORATION
                              ONE F.N.B. BOULEVARD
                              HERMITAGE, PA 16148
                    (Name and address of agent for service)

                                 (412) 981-6000
         (Telephone number, including area code, of agent for service)
                              -------------------

                        CALCULATION OF REGISTRATION FEE
=========================================================================================================================
                                                   Proposed maximum       Proposed maximum
 Title of securities to        Amount to be       offering price per     aggregate offering        Amount of
      be registered             registered               share                  price          registration fee
-------------------------------------------------------------------------------------------------------------------------
Common stock, par value         300,000              $18.69 (2)             $5,607,000            $1,480.25
     $2.00 per share
=========================================================================================================================
(1) There are also being registered hereunder such number of additional shares
of Common Stock which may become available for purchase in accordance with the
provisions of the Plan in the event of any change in the outstanding shares of
F.N.B. Corporation, including a stock dividend or stock split.

(2) Estimated solely for the purposes of calculating the registration fee:
Calculated pursuant to Rule 457(c) based upon the market value per share of
F.N.B. Corporation common stock as of May 26, 2000.
2

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents filed by F.N.B. Corporation ("FNB" or the
"Corporation") with the Securities and Exchange Commission (the "Commission")
are incorporated by reference into this Registration Statement:

                           1. FNB's Annual Report on Form 10-K for the fiscal
                  year ended December 31, 1999.

                           2. FNB's definitive Proxy Statement filed with the
                  Commission pursuant to Section 14 of the Securities Exchange
                  Act of 1934, as amended, (the "Exchange Act"), in connection
                  with the Annual Meeting of Shareholders of FNB held on April
                  17, 2000.

                           3. The description of FNB's Common Stock, par value
                  $2.00 per share (the "Common Stock"), contained in FNB's
                  Registration Statement filed under Section 12 of the Exchange
                  Act, including all amendments and reports updating such
                  description.

                  The consolidated financial statements of FNB at December 31,
1999 and 1998, and for each of the three years in the period ended December 31,
1999, have been audited by Ernst & Young LLP, independent auditors, as set forth
in their report thereon, incorporated by reference in FNB's Annual Report on
Form 10-K dated March 13, 2000, and incorporated herein by reference. As to
1998, their report is based, in part, on the report of Bobbitt, Pittenger &
Company, P.A., independent auditors, who audited Guaranty Bank & Trust Company.
As to 1997, their report is based, in part, on the reports of Hacker, Johnson,
Cohen & Grieb PA, independent auditors, who audited Seminole Bank and Citizens
Holding Corporation and Bobbitt, Pittenger & Company, P.A., independent
auditors, who audited Guaranty Bank & Trust Company. The financial statements
referred to above are included in reliance upon such reports given on the
authority of said firms as experts in accounting and auditing.

                  All documents subsequently filed by FNB with the Commission
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the
date of this Registration Statement, but prior to the filing of a post-effective
amendment to this Registration Statement which indicates that all securities
offered by this Registration Statement have been sold or which deregisters all
such securities then remaining unsold, shall be deemed to be incorporated by
reference into this Registration Statement. Each document incorporated by
reference into this Registration Statement shall be deemed to be a part of this
Registration Statement from the date of the filing of such document with the
Commission until the information contained therein is superseded or updated by
any subsequently filed document which is incorporated by reference into this
Registration Statement or by any document which constitutes part of the
prospectus relating to the F.N.B. Corporation 401(k) Plan meeting the
requirements of Section 10(a) of the Securities Act of 1933, as amended (the
"Securities Act").

ITEM 4. DESCRIPTION OF SECURITIES.

                  The class of securities to be offered under the Registration
Statement is registered under Section 12 of the Exchange Act.
3

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

                  The legality of the securities offered hereby will be passed
upon by Cohen & Grigsby, P.C., Pittsburgh, Pennsylvania, counsel to FNB.

ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

                  The effect of charter, by-law, statutory and other provisions
whereby the directors and officers of FNB may be insured or indemnified against
liability as officers and directors are set out below:

                  Numbered Paragraph 6.b. of the Articles of Incorporation, as
amended, of FNB provides as follows:

                  Directors and Officers of the Corporation shall be indemnified
        as of right to the fullest extent now or hereafter permitted by law in
        connection with any actual or threatened action, suit or proceedings,
        civil, criminal, administrative, investigative or other (whether brought
        by or in the right of the Corporation or otherwise), arising out of
        their service to the Corporation or to another organization at the
        request of the Corporation, or because of their positions with the
        Corporation. Persons who are not Directors or Officers of the
        Corporation may be similarly indemnified in respect of such service to
        the extent authorized at any time by the Board of Directors of the
        Corporation. The Corporation may purchase and maintain insurance to
        protect itself and any such Director, Officer or other person against
        any liability, cost or expense asserted against or incurred by him in
        respect of such service, whether or not the Corporation would have the
        power to indemnify him against such liability by law or under the
        provisions of this paragraph. The provisions of this paragraph shall be
        applicable to persons who have ceased to be Directors or Officers, and
        shall inure to the benefit of the heirs, executors and administrators of
        persons entitled to indemnity hereunder.

                  Article IX of the Bylaws of the Corporation provides that the
Corporation shall indemnify each director and officer of the Corporation and of
its controlled subsidiaries made or threatened to be made a party to any civil,
criminal, administrative or investigative action, suit or proceeding (whether
brought by or in the name of the Corporation or otherwise) arising out of such
director's or officer's service to the Corporation or to another organization at
the Corporation's request against all expenses (including attorneys' fees),
judgments, fines and amounts paid in settlement actually and reasonably incurred
by such director and officer in connection with such action, suit or proceeding.
Indemnification shall not be made with respect to actions, suits or proceedings
where the act or omission giving rise to the claim for indemnification has been
determined to have constituted willful misconduct or recklessness or where
prohibited by law. In addition, expenses incurred by each director and officer
in defending any such action, suit or proceeding, shall be paid by the
Corporation in advance of the final disposition of such action, suit or
proceeding if an undertaking (in form and scope satisfactory to the Corporation)
shall have been furnished to the Corporation to repay amounts so advanced if and
to the extent it shall ultimately be determined that such officer or director is
not entitled to indemnification and certain other conditions shall have been
satisfied. The Corporation may purchase and maintain insurance, create a fund of
any nature, grant a security interest or otherwise secure or insure in any
manner its indemnification obligations.

                  Section 1741 of the Pennsylvania Business Corporation Law
provides that a corporation shall (subject to the provisions described in the
second succeeding paragraph) have the power to indemnify any person who was or
is a party, or is threatened to be made a party, to any threatened, pending or
completed action or proceeding, whether civil, criminal, administrative or
investigative (other than an action by or in the right of the corporation), by
reason of the fact that such person is or was a representative of the
corporation, or is or was serving at the request of the corporation as a
representative

                                      -2-
4

of another domestic or foreign corporation for profit or not-for-profit,
partnership, joint venture, trust or other enterprise, against expenses
(including attorneys' fees), judgments, fines and amounts paid in settlement
actually and reasonably incurred by such person in connection with the action or
proceeding if such person acted in good faith and in a manner he reasonably
believed to be in, or not opposed to, the best interests of the corporation and,
with respect to any criminal proceeding, had no reasonable cause to believe his
conduct was unlawful. The termination of any action or proceeding by judgment,
order, settlement or conviction, or upon a plea of nolo contendere or its
equivalent shall not of itself create a presumption that such person did not act
in good faith and in a manner which he reasonably believed to be in, or not
opposed to, the best interests of the corporation and, with respect to any
criminal proceeding, had reasonable cause to believe that his conduct was
unlawful.

                  Section 1742 of the Pennsylvania Business Corporation Law
provides that a corporation shall (subject to the provisions described in the
succeeding paragraph) have the power to indemnify any person who was or is a
party, or is threatened to be made a party, to any threatened, pending or
completed action by or in the right of the corporation to procure a judgment in
its favor by reason of the fact that such person is or was a representative of
the corporation, or is or was serving at the request of the corporation as a
representative of another domestic or foreign corporation for profit or
not-for-profit, partnership, joint venture, trust or other enterprise against
expenses (including attorneys' fees) actually and reasonably incurred by such
person in connection with the defense or settlement of the action if such person
acted in good faith and in a manner he reasonably believed to be in, or not
opposed to, the best interests of the corporation. Indemnification shall not be
made in respect of any claim, issue or matter as to which such person has been
adjudged to be liable to the corporation unless and only to the extent that the
court of common pleas of the county in which the registered office of the
corporation is located or the court in which the action was brought determines
upon application that, despite the adjudication of liability but in view of all
the circumstances of the case, such person is fairly and reasonably entitled to
indemnity for such expenses that the court of common pleas or other court deems
proper.

                  Under Section 1744 of the Pennsylvania Business Corporation
Law, any such indemnification (unless ordered by a court) shall be made by the
corporation only as authorized in the specific case upon a determination that
indemnification of the representative is proper in the circumstances because
such person has met the applicable standard of conduct. Such determination shall
be made:

                  (1) By the Board of Directors by a majority vote of a quorum
         consisting of directors who were not parties to the action or
         proceeding; or

                  (2) If such quorum is not obtainable or, even if obtainable a
         majority vote of a quorum of disinterested directors so directs, by
         independent legal counsel in a written opinion; or

                  (3) By the shareholders.

                  Notwithstanding the above, Section 1743 provides that to the
extent that a representative of the corporation has been successful on the
merits or otherwise in defense of any action or proceeding referred to above, or
in defense of any claim, issue or matter therein, such person shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred by such person in connection therewith.

                  Under Section 1745 of the Pennsylvania Business Corporation
Law, expenses (including attorneys' fees) incurred in defending any action or
proceeding may be paid by the corporation in advance of the final disposition of
the action or proceeding upon receipt of an undertaking by or on behalf of the
representative to repay such amount if it is ultimately determined that such
person is not entitled to be indemnified by the corporation.

                                      -3-
5

                  Section 1746 of the Pennsylvania Business Corporation Law
further provides that the indemnification provided by Sections 1741, 1742 and
1743 and the advancement of expenses provided by Section 1745 shall not be
deemed exclusive of any other rights to which a person seeking indemnification
or advancement of expenses may be entitled under any bylaw, agreement, vote of
shareholders, disinterested directors or otherwise, both as to action in his
official capacity and as to action in another capacity while holding that
office. A corporation may create a fund of any nature, which may, but need not
be, under the control of a trustee, or otherwise secure or insure in any manner
its indemnification obligations, whether arising under or pursuant to Section
1746 or otherwise. Indemnification pursuant to Section 1746 shall not be made in
any case where the act or failure to act giving rise to the claim for
indemnification is determined by a court to have constituted willful misconduct
or recklessness.

                  Indemnification pursuant to Section 1746 under any bylaw,
agreement, vote of shareholders, or directors or otherwise may be granted for
any action taken or any failure to take any action and may be made whether or
not the corporation would have the power to indemnify the person under any other
provision of law except as provided in such Section 1746 and whether or not the
indemnified liability arises or arose from any threatened, pending or completed
action by or in the right of the corporation. Section 1746 declares such
indemnification to be consistent with the public policy of Pennsylvania.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

                  Not applicable.

ITEM 8. EXHIBITS.

                  4.1               F.N.B. Corporation 401(k) Plan (incorporated
                                    by reference to Exhibit 4.1 of the
                                    Corporation's Registration Statement on Form
                                    S-8, filed August 13, 1992, File Number
                                    33-50780).

                  5.1               Opinion of Cohen & Grigsby, P.C. regarding
                                    legality of the securities being registered.

                  23.1              Consent of Ernst & Young LLP.

                  23.2              Consent of Bobbitt Pittinger & Company, P.A.

                  23.3              Consent of Hacker, Johnson, Cohen & Grieb PA

                  23.4              Consent of Cohen & Grigsby, P.C., included
                                    in opinion filed as Exhibit 5.1.

                  24                Power of Attorney

ITEM 9. UNDERTAKINGS.

(a)               Rule 415 Offering undertaking:

                  The undersigned registrant hereby undertakes:

                  (1) To file, during any period in which offers or sales are
being made, a post-effective amendment to this registration statement:

                                      -4-
6

                       (i)      To include any prospectus required by Section
                                10(a)(3) of the Securities Act of 1933;

                       (ii)     To reflect in the prospectus any facts or events
                                arising after the effective date of the
                                registration statement (or the most recent
                                post-effective amendment thereof) which,
                                individually or in the aggregate, represents a
                                fundamental change in the information set forth
                                in the registration statement;

                       (iii)    To include any material information with respect
                                to the plan of distribution not previously
                                disclosed in the registration statement or any
                                material change to such information in the
                                registration statement;

provided, however, that paragraphs (a)(l)(i) and (a)(l)(ii) do not apply if the
registration statement is on Form S-3 or Form S-8 and the information required
to be included in a post-effective amendment by those paragraphs is contained in
periodic reports filed by the registrants pursuant to Section 13 or Section
15(d) of the Securities Exchange Act of 1934 that are incorporated by reference
in the registration statement.

                  (2) That, for the purpose of determining any liability under
the Securities Act of 1933, each post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

(b)               Filings Incorporating Subsequent Exchange Act Documents by
                  Reference undertaking:

                  The undersigned registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act of 1933, each
filing of the registrant's annual report pursuant to Section 13(a) or Section
15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing
of an employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

(c)               Filing of Registration Statement on Form S-8 undertaking:

                  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the registrant of expenses
incurred or paid by a director, officer or controlling person of the registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.

                                      -5-
7

                                   SIGNATURES

                  The Registrant. Pursuant to the requirements of the Securities
Act of 1933, the registrant certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form S-8 and has duly caused
this registration statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Hermitage, Commonwealth of
Pennsylvania, on May 31, 2000.

                                          F.N.B. CORPORATION

                                          By /s/ Peter Mortensen
                                             -----------------------------------
                                             Peter Mortensen, Chairman and Chief
                                             Executive Officer

                  Pursuant to the requirements of the Securities Act of 1933,
this registration statement has been signed by the following persons in the
capacities and on the dates indicated.
/s/ Peter Mortensen                      Chairman, Chief Executive Officer      May 31, 2000
---------------------------------        and Director (Principal Executive
Peter Mortensen                          Officer)

/s/ Stephen J. Gurgovits                 Vice Chairman and Director             May 31, 2000
---------------------------------
Stephen J. Gurgovits

/s/ Gary L. Tice                         President, Chief Operating Officer     May 31, 2000
---------------------------------        and Director
Gary L. Tice

/s/ John D. Waters                       Vice President and Chief Financial     May 31, 2000
---------------------------------        Officer (Principal Accounting
John D. Waters                           Officer)

                                         Director                               May 31, 2000
---------------------------------
W. Richard Blackwood

                                         Director                               May 31, 2000
---------------------------------
Alan C. Bomstein
-6-
8
/s/ William B. Campbell                  Director                               May 31, 2000
---------------------------------
William B. Campbell

/s/ Charles T. Cricks                    Director                               May 31, 2000
---------------------------------
Charles T. Cricks

/s/ Henry M. Ekker                       Director                               May 31, 2000
---------------------------------
Henry M. Ekker

/s/ James S. Lindsay                     Director                               May 31, 2000
---------------------------------
James S. Lindsay

/s/ Paul P. Lynch                        Director                               May 31, 2000
---------------------------------
Paul P. Lynch

                                         Director                               May 31, 2000
---------------------------------
Edward J. Mace

                                         Director                               May 31, 2000
---------------------------------
Robert S. Moss

                                         Director                               May 31, 2000
---------------------------------
William A. Quinn

/s/ William J. Strimbu                   Director                               May 31, 2000
---------------------------------
William J. Strimbu

/s/ Archie O. Wallace                    Director                               May 31, 2000
---------------------------------
Archie O. Wallace

/s/ James T. Weller                      Director                               May 31, 2000
---------------------------------
James T. Weller

                                         Director                               May 31, 2000
---------------------------------
Eric J. Werner

                                         Director                               May 31, 2000
---------------------------------
Benjamin Wiley

                                         Director                               May 31, 2000
---------------------------------
Donna C. Winner
-7-
9

                                  EXHIBIT INDEX

                  4.1               F.N.B. Corporation 401(k) Plan (incorporated
                                    by reference to Exhibit 4.1 of the
                                    Corporation's Registration Statement on Form
                                    S-8, filed August 13, 1992, File Number
                                    33-50780.

                  5.1               Opinion of Cohen & Grigsby, P.C. regarding
                                    legality of the securities being registered.

                  23.1              Consent of Ernst & Young LLP.

                  23.2              Consent of Bobbitt Pittinger & Company, P.A.

                  23.3              Consent of Hacker, Johnson, Cohen & Grieb PA

                  23.4              Consent of Cohen & Grigsby, P.C., included
                                    in opinion filed as Exhibit 5.1.

                  24                Power of Attorney