<PAGE>

                                                     Registration No. 333-______

      As filed with the Securities and Exchange Commission on September 22, 1999
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION

                             Washington, DC 20549

                       ________________________________

                                   FORM S-8

                            REGISTRATION STATEMENT

                                     Under

                          the Securities Act of 1933

                       ________________________________

                           PathoGenesis Corporation
            (Exact Name of Registrant as Specified in Its Charter)

            DELAWARE                                        91-1542150
   (State or Other Jurisdiction                          (I.R.S. Employer
 of Incorporation or Organization)                      Identification No.)

                            201 Elliott Avenue West
                           Seattle, Washington 98119
                   (Address of Principal Executive Offices)


                           PathoGenesis Corporation
                                1999 Stock Plan
                           (Full Title of the Plan)


       Cameron S. Avery                                  Copies to:
       General Counsel                                 Woon-Wah Siu
    PathoGenesis Corporation                        Bell, Boyd & Lloyd
  5215 Old Orchard Road, Suite 900              Three First National Plaza
     Skokie, Illinois 60077                       Chicago, Illinois 60602
         (847) 583-8050                                (312) 372-1121

          (Name, Address and Telephone Number of Agents for Service)

                       ________________________________

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=================================================================================================================
                                                               Proposed        Proposed
                                             Amount            Maximum         Maximum           Amount of
        Title of Each Class of                to be         Offering Price    Aggregate         Registration
     Securities to be Registered          Registered(1)       Per Share     Offering Price          Fee
-----------------------------------------------------------------------------------------------------------------
<S>                                       <C>               <C>             <C>                 <C>
Common Stock, par value $.001 per share  510,000 Shares     $13.88(2)       $7,076,250(2)       $1,967(2)
-----------------------------------------------------------------------------------------------------------------
Common Stock, par value $.001 per share  290,000 Shares     $15.56(3)       $4,513,125(3)       $1,255(3)
=================================================================================================================
</TABLE>

(1)  Includes 800,000 Preferred Stock Purchase Rights evidenced by certificates
     of shares of common stock that automatically trade with such common stock.
     Also includes an indeterminate number of additional shares, and the
     associated Preferred Stock Purchase Rights, that may become issuable under
     the antidilution and other adjustment provisions of the PathoGenesis
     Corporation 1999 Stock Plan pursuant to Rule 416(a) of the Securities Act
     of 1933, as amended.
(2)  Based on the weighted average exercise price of currently outstanding
     options under the 1999 Stock Plan.
(3)  In accordance with Rule 457(h), calculated on the basis of the average of
     the high and low sale prices of the Registrant's common stock as quoted in
     the consolidated reporting system of the Nasdaq National Market on
     September 20, 1999, as reported by The Wall Street Journal (Midwest
     Edition).

================================================================================
<PAGE>

                                    PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.

     Not required to be included herewith.

Item 2.  Registrant Information and Employee Plan Annual Information.

     Not required to be included herewith.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

     We, PathoGenesis Corporation, are filing this registration statement on
Form S-8 to register shares of our common stock, par value $.001 per share.

     We incorporate by reference the following documents in this registration
statement:

               (a)  Our annual report on Form 10-K for the fiscal year ended
     December 31, 1998 (File No. 0-27150);

               (b)  Our quarterly reports on Form 10-Q for the quarters ended
     March 31, 1999 and June 30, 1999 (File No. 0-27150);

               (c)  The description of our common stock set forth under the
     caption "Description of Capital Stock - Common Stock" in our prospectus
     constituting a part of the registration statement on Form S-1 (Reg. No.
     333-22297), filed on February 25, 1997; and

               (d)  The description of our Preferred Stock Purchase Rights in
     the registration statement on Form 8-A filed on July 10, 1997, for the
     registration of those Rights under Section 12(g) of the Securities Exchange
     Act of 1934, as amended by amendment filed on April 15, 1999 (File No. 0-
     27150).

     Incorporation by reference means that we are making the documents listed
above a part of this registration statement by referring to them and declaring
that you should consider them to be part of this registration statement as if
they were fully copied in this registration statement.  We also incorporate by
reference all documents we  subsequently file under Sections 13(a), 13(c), 14
and 15(d) of the Securities Exchange Act of 1934, before we file a post-
effective amendment to indicate that all shares of common stock offer by this
registration statement have been sold or to deregister all the shares then
remaining unsold.  For purposes of this registration statement, you should
consider any statement contained in a document incorporated by reference in this
registration statement to be modified or superseded to the extent that a
statement contained in this registration statement or in any other subsequently
filed document which also is incorporated by reference in this registration
statement modifies or replaces such statement.  You should not consider any
statement so modified or superseded, except as so modified or superseded, to be
a part of this registration statement.

Item 4.  Description of Securities.

     Not applicable.

                                       1
<PAGE>

Item 5.  Interests of Named Experts and Counsel.

     Not applicable.

Item 6.  Indemnification of Directors and Officers.

     Section 145 of the Delaware General Corporation Law authorizes a Delaware
corporation to indemnify any director or officer against expenses, judgments,
fines and settlements actually and reasonably incurred by such person in
connection with any action, suit or proceeding, if such director or officer
acted in good faith and in a manner such person reasonably believed to be in or
not opposed to the best interests of the corporation and, with respect to any
criminal action or proceeding, had no reasonable cause to believe his or her
conduct was unlawful, except that no indemnification shall be made in connection
with any action by or in the right of the corporation if such person is adjudged
to be liable to the corporation, unless the court determines that despite the
adjudication of liability such person is fairly and reasonably entitled to
indemnity for such expense that the court shall deem proper.  Said section
further provides that to the extent that any such person is successful on the
merits or otherwise in defense of any action such director or officer shall be
indemnified against expenses actually and reasonably incurred by him or her.  In
addition, a Delaware corporation is authorized to purchase insurance on behalf
of its directors and officers against liabilities whether or not in the
circumstances the corporation would have the power to indemnify against such
liabilities under said section.

     The Company's Amended and Restated Certificate of Incorporation provides
for indemnification of the Company's directors, officers, employees and agents,
to the fullest extent permitted by the Delaware General Corporation Law, against
all expense, liability and loss reasonably incurred or suffered by each such
person in connection with any action, suit, or proceeding to which such person
was or is made a party or is threatened to be a party by reason of the fact that
such person is a director, officer, employee or agent of the Company; provided,
however, except as provided in the Amended and Restated Certificate of
Incorporation with respect to proceedings to enforce rights to indemnification,
the Company shall indemnify any such person in connection with a proceeding
initiated by such person if the proceeding was authorized by the board of
directors of the Company.  The Company has obtained directors and officers
insurance covering its directors and executive officers.

     The Company's Amended and Restated Certificate of Incorporation eliminates,
to the fullest extent permitted by Delaware law, liability of a director to the
Company or its stockholders for monetary damages for breach of the director's
fiduciary duty of care except for liability where the director (a) breaches his
or her duty of loyalty to the Company or its shareholders, (b) fails to act in
good faith or engages in intentional misconduct or knowing violation of law, (c)
authorized a payment of an illegal dividend or stock repurchase, or (d) obtains
an improper personal benefit.  While liability for monetary damages has been
eliminated, equitable remedies such as injunctive relief or rescission remain
available.  In addition, a director is not relieved of his or her
responsibilities under any other law, including the federal securities laws.

     Insofar as indemnification by the Company for liabilities arising under the
Securities Act, may be permitted to directors, officers, and controlling persons
of the Company pursuant to the foregoing, the Company has been advised that in
the opinion of the Securities and Exchange Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable.

Item 7.  Exemption From Registration Claimed.

     Not applicable.

                                       2
<PAGE>

Item 8.  Exhibits.

     We incorporate by reference the Exhibit Index which appears at the end of
this registration statement.  That Index lists the exhibits to this registration
statement.

Item 9.  Undertakings.

     (a)  The Company hereby undertakes:

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

                    (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 this registration statement
               (or the most recent post-effective amendment thereof) which,
               individually or in the aggregate, represent a fundamental change
               in the information set forth in this registration statement.
               Notwithstanding the foregoing, any increase or decrease in volume
               of securities offered (if the total dollar value of securities
               offered would not exceed that which was registered) and any
               deviation from the low or high end of the estimated maximum
               offering range may be reflected in the form of prospectus filed
               with the Commission pursuant to Rule 424(b) if, in the aggregate,
               the changes in volume and price represent no more than a 20
               percent change in the maximum aggregate offering price set forth
               in the "Calculation of Registration Fee" table in the effective
               registration statement;

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

          provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
          apply if the information required to be included in a post-effective
          amendment by those paragraphs is contained in periodic reports filed
          by the Company pursuant to Section 13 or Section 15(d) of the
          Securities Exchange Act of 1934 that are incorporated by reference in
          this registration statement.

               (2)  That, for the purpose of determining any liability under the
          Securities Act of 1933, each such 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)  The Company hereby undertakes that, for purposes of determining any
liability under the Securities Act of 1933, each filing of the Company'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 this 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)-(g)  Not applicable.

     (h)  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Company pursuant to the foregoing provisions, or otherwise, the

                                       3
<PAGE>

Company has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act of 1933 and is, therefore, unenforceable. In the event that a
claim for indemnification against such liabilities (other than the payment by
the Company of expenses incurred or paid by a director, officer or controlling
person of the Company 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 Company 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 Securities
Act of 1933 and will be governed by the final adjudication of such issue.

     (i)-(j)  Not applicable.

                                       4
<PAGE>

                                  SIGNATURES

          Pursuant to the requirements of the Securities Act of 1933, the
Company 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 Skokie, State of Illinois, on September 22, 1999.

                                PATHOGENESIS CORPORATION


                                By           /s/ Alan R. Meyer
                                    --------------------------------------
                                                 Alan R. Meyer
                                           Executive Vice President

     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/ Alan R. Meyer        Executive Vice President, Chief      September 22, 1999
--------------------
Alan R. Meyer            Financial Officer and Director
                         (Principal Financial and
                          Accounting Officer)

Wilbur H. Gantz          Chairman, Chief Executive     )
                         Officer, President and        )
                         Director (Principal           )
                         Executive Officer)            )
                                                       )
John Gordon              Director                      )
                                                       )
                                                       )
Elizabeth M. Greetham    Director                      ) By:  /s/ Alan R. Meyer
                                                       )     -------------------
                                                       )        Alan R. Meyer
                                                       )       Attorney-in-Fact
Michael J. Montgomery    Director                      )      September 22, 1999
                                                       )
                                                       )
Arthur W. Nienhuis       Director                      )
                                                       )
                                                       )
Talat M. Othman          Director                      )
                                                       )
                                                       )
Eugene L. Step           Director                      )
                                                       )
                                                       )
James R. Tobin           Director                      )
                                                       )
                                                       )
Fred Wilpon              Director                      )

                                       5
<PAGE>

(Being the principal executive officer, the principal financial and accounting
officer and a majority of the directors of PathoGenesis Corporation.)

ORIGINAL POWER OF ATTORNEY AUTHORIZING WILBUR H. GANTZ AND ALAN R. MEYER TO
EXECUTE THIS REGISTRATION STATEMENT FOR EACH OF MS. GREETHAM AND MESSRS. GANTZ,
GORDON, MEYER, MONTGOMERY, NIENHUIS, OTHMAN, STEP, TOBIN AND WILPON HAS BEEN
EXECUTED AND FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       6
<PAGE>

                                 Exhibit Index

          The following are filed as part of this registration statement.

Exhibit Number               Description of Document
--------------               -----------------------

    4.1             Composite Certificate of Incorporation of PathoGenesis
                    Corporation, as amended (incorporated reference to Exhibit
                    3.1(d) of quarterly report on Form 10-Q for the three months
                    ended March 31, 1998, File No. 0-27150).

    4.1(a)          Amended and Restated Certificate of Incorporation, as
                    amended (incorporated by reference to Exhibit 3.1 to
                    registration statement on Form S-1, Registration No. 333-
                    22297).

    4.1(b)          Certificate of Amendment of Amended and Restated Certificate
                    of Incorporation (incorporated by reference to Exhibit
                    4.1(b) to registration statement on Form S-8, Registration
                    No. 333-45571).

    4.2             By-laws of the Company, as amended through June 3, 1999
                    (incorporated by reference to Exhibit 3.2 to quarterly
                    report on Form 10-Q for the three months ended June 30,
                    1999, File No. 0-27150).

    4.3             Certificate of Designations (incorporated by reference to
                    Exhibit 4.1(b) to registration statement on Form S-8,
                    Registration No. 333-45571).

    4.4             PathoGenesis Corporation PathoGenesis Corporation 1999 Stock
                    Plan (incorporated by reference to Appendix A to
                    PathoGenesis' notice and proxy statement dated April 19,
                    1999, File No. 0-27150).

    4.4(a)          Form of Stock Option Agreement for 1999 Stock Plan
                    (incorporated by reference to Exhibit 4.10 to quarterly
                    report on Form 10-Q for the three months ended June 30,
                    1999, File No. 0-27150).

    4.5             Rights Agreement, dated as of June 25, 1997, between
                    PathoGenesis Corporation and Harris Trust and Savings Bank
                    as Rights Agent, including the form of Right Certificate as
                    Exhibit B (incorporated by reference to Exhibit 1 to current
                    report on Form 8-K filed on July 10, 1997, File No.
                    0-27150).

    4.5(a)          First Amendment, dated as of March 8, 1998, to Rights
                    Agreement between PathoGenesis Corporation and Harris Trust
                    and Savings Bank, as Rights Agent (incorporated by reference
                    to Exhibit 4.1(bb) to annual report on Form 10-K for 1997,
                    File No. 0-27150).

    4.5(b)          Amendment of Rights Plan, dated as of April 13, 1999,
                    between PathoGenesis Corporation and Harris Trust and
                    Savings Bank as Rights Agent (incorporated by reference to
                    Exhibit 4.1(bbb) to amendment to registration statement on
                    Form 8-A/A, filed on April 15, 1999, File No. 0-27150).

    5               Opinion of Bell, Boyd & Lloyd.

   23.1             Consent of KPMG LLP.

   23.2             Consent of Bell, Boyd & Lloyd (included in Exhibit 5).

   24               Power of Attorney
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Registration No. 333-______

      As filed with the Securities and Exchange Commission on September 22, 1999
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION

                             Washington, DC 20549

                       ________________________________

                                   FORM S-8

                            REGISTRATION STATEMENT

                                     Under

                          the Securities Act of 1933

                       ________________________________

                           PathoGenesis Corporation
            (Exact Name of Registrant as Specified in Its Charter)

            DELAWARE                                        91-1542150
   (State or Other Jurisdiction                          (I.R.S. Employer
 of Incorporation or Organization)                      Identification No.)

                            201 Elliott Avenue West
                           Seattle, Washington 98119
                   (Address of Principal Executive Offices)

                           PathoGenesis Corporation
                                1999 Stock Plan
                           (Full Title of the Plan)

       Cameron S. Avery                                  Copies to:
       General Counsel                                 Woon-Wah Siu
    PathoGenesis Corporation                        Bell, Boyd & Lloyd
  5215 Old Orchard Road, Suite 900              Three First National Plaza
     Skokie, Illinois 60077                       Chicago, Illinois 60602
         (847) 583-8050                                (312) 372-1121

          (Name, Address and Telephone Number of Agents for Service)

                       ________________________________

                        CALCULATION OF REGISTRATION FEE
=================================================================================================================
                                                               Proposed        Proposed
                                             Amount            Maximum         Maximum           Amount of
        Title of Each Class of                to be         Offering Price    Aggregate         Registration
     Securities to be Registered          Registered(1)       Per Share     Offering Price          Fee
-----------------------------------------------------------------------------------------------------------------
Common Stock, par value $.001 per share  510,000 Shares     $13.88(2)       $7,076,250(2)       $1,967(2)
-----------------------------------------------------------------------------------------------------------------
Common Stock, par value $.001 per share  290,000 Shares     $15.56(3)       $4,513,125(3)       $1,255(3)
=================================================================================================================
(1)  Includes 800,000 Preferred Stock Purchase Rights evidenced by certificates
     of shares of common stock that automatically trade with such common stock.
     Also includes an indeterminate number of additional shares, and the
     associated Preferred Stock Purchase Rights, that may become issuable under
     the antidilution and other adjustment provisions of the PathoGenesis
     Corporation 1999 Stock Plan pursuant to Rule 416(a) of the Securities Act
     of 1933, as amended.
(2)  Based on the weighted average exercise price of currently outstanding
     options under the 1999 Stock Plan.
(3)  In accordance with Rule 457(h), calculated on the basis of the average of
     the high and low sale prices of the Registrant's common stock as quoted in
     the consolidated reporting system of the Nasdaq National Market on
     September 20, 1999, as reported by The Wall Street Journal (Midwest
     Edition).

================================================================================
PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.  Plan Information.

     Not required to be included herewith.

Item 2.  Registrant Information and Employee Plan Annual Information.

     Not required to be included herewith.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

     We, PathoGenesis Corporation, are filing this registration statement on
Form S-8 to register shares of our common stock, par value $.001 per share.

     We incorporate by reference the following documents in this registration
statement:

               (a)  Our annual report on Form 10-K for the fiscal year ended
     December 31, 1998 (File No. 0-27150);

               (b)  Our quarterly reports on Form 10-Q for the quarters ended
     March 31, 1999 and June 30, 1999 (File No. 0-27150);

               (c)  The description of our common stock set forth under the
     caption "Description of Capital Stock - Common Stock" in our prospectus
     constituting a part of the registration statement on Form S-1 (Reg. No.
     333-22297), filed on February 25, 1997; and

               (d)  The description of our Preferred Stock Purchase Rights in
     the registration statement on Form 8-A filed on July 10, 1997, for the
     registration of those Rights under Section 12(g) of the Securities Exchange
     Act of 1934, as amended by amendment filed on April 15, 1999 (File No. 0-
     27150).

     Incorporation by reference means that we are making the documents listed
above a part of this registration statement by referring to them and declaring
that you should consider them to be part of this registration statement as if
they were fully copied in this registration statement.  We also incorporate by
reference all documents we  subsequently file under Sections 13(a), 13(c), 14
and 15(d) of the Securities Exchange Act of 1934, before we file a post-
effective amendment to indicate that all shares of common stock offer by this
registration statement have been sold or to deregister all the shares then
remaining unsold.  For purposes of this registration statement, you should
consider any statement contained in a document incorporated by reference in this
registration statement to be modified or superseded to the extent that a
statement contained in this registration statement or in any other subsequently
filed document which also is incorporated by reference in this registration
statement modifies or replaces such statement.  You should not consider any
statement so modified or superseded, except as so modified or superseded, to be
a part of this registration statement.

Item 4.  Description of Securities.

     Not applicable.

                                       1
Item 5.  Interests of Named Experts and Counsel.

     Not applicable.

Item 6.  Indemnification of Directors and Officers.

     Section 145 of the Delaware General Corporation Law authorizes a Delaware
corporation to indemnify any director or officer against expenses, judgments,
fines and settlements actually and reasonably incurred by such person in
connection with any action, suit or proceeding, if such director or officer
acted in good faith and in a manner such person reasonably believed to be in or
not opposed to the best interests of the corporation and, with respect to any
criminal action or proceeding, had no reasonable cause to believe his or her
conduct was unlawful, except that no indemnification shall be made in connection
with any action by or in the right of the corporation if such person is adjudged
to be liable to the corporation, unless the court determines that despite the
adjudication of liability such person is fairly and reasonably entitled to
indemnity for such expense that the court shall deem proper.  Said section
further provides that to the extent that any such person is successful on the
merits or otherwise in defense of any action such director or officer shall be
indemnified against expenses actually and reasonably incurred by him or her.  In
addition, a Delaware corporation is authorized to purchase insurance on behalf
of its directors and officers against liabilities whether or not in the
circumstances the corporation would have the power to indemnify against such
liabilities under said section.

     The Company's Amended and Restated Certificate of Incorporation provides
for indemnification of the Company's directors, officers, employees and agents,
to the fullest extent permitted by the Delaware General Corporation Law, against
all expense, liability and loss reasonably incurred or suffered by each such
person in connection with any action, suit, or proceeding to which such person
was or is made a party or is threatened to be a party by reason of the fact that
such person is a director, officer, employee or agent of the Company; provided,
however, except as provided in the Amended and Restated Certificate of
Incorporation with respect to proceedings to enforce rights to indemnification,
the Company shall indemnify any such person in connection with a proceeding
initiated by such person if the proceeding was authorized by the board of
directors of the Company.  The Company has obtained directors and officers
insurance covering its directors and executive officers.

     The Company's Amended and Restated Certificate of Incorporation eliminates,
to the fullest extent permitted by Delaware law, liability of a director to the
Company or its stockholders for monetary damages for breach of the director's
fiduciary duty of care except for liability where the director (a) breaches his
or her duty of loyalty to the Company or its shareholders, (b) fails to act in
good faith or engages in intentional misconduct or knowing violation of law, (c)
authorized a payment of an illegal dividend or stock repurchase, or (d) obtains
an improper personal benefit.  While liability for monetary damages has been
eliminated, equitable remedies such as injunctive relief or rescission remain
available.  In addition, a director is not relieved of his or her
responsibilities under any other law, including the federal securities laws.

     Insofar as indemnification by the Company for liabilities arising under the
Securities Act, may be permitted to directors, officers, and controlling persons
of the Company pursuant to the foregoing, the Company has been advised that in
the opinion of the Securities and Exchange Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable.

Item 7.  Exemption From Registration Claimed.

     Not applicable.

                                       2
Item 8.  Exhibits.

     We incorporate by reference the Exhibit Index which appears at the end of
this registration statement.  That Index lists the exhibits to this registration
statement.

Item 9.  Undertakings.

     (a)  The Company hereby undertakes:

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

                    (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 this registration statement
               (or the most recent post-effective amendment thereof) which,
               individually or in the aggregate, represent a fundamental change
               in the information set forth in this registration statement.
               Notwithstanding the foregoing, any increase or decrease in volume
               of securities offered (if the total dollar value of securities
               offered would not exceed that which was registered) and any
               deviation from the low or high end of the estimated maximum
               offering range may be reflected in the form of prospectus filed
               with the Commission pursuant to Rule 424(b) if, in the aggregate,
               the changes in volume and price represent no more than a 20
               percent change in the maximum aggregate offering price set forth
               in the "Calculation of Registration Fee" table in the effective
               registration statement;

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

          provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
          apply if the information required to be included in a post-effective
          amendment by those paragraphs is contained in periodic reports filed
          by the Company pursuant to Section 13 or Section 15(d) of the
          Securities Exchange Act of 1934 that are incorporated by reference in
          this registration statement.

               (2)  That, for the purpose of determining any liability under the
          Securities Act of 1933, each such 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)  The Company hereby undertakes that, for purposes of determining any
liability under the Securities Act of 1933, each filing of the Company'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 this 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)-(g)  Not applicable.

     (h)  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Company pursuant to the foregoing provisions, or otherwise, the

                                       3
Company has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act of 1933 and is, therefore, unenforceable. In the event that a
claim for indemnification against such liabilities (other than the payment by
the Company of expenses incurred or paid by a director, officer or controlling
person of the Company 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 Company 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 Securities
Act of 1933 and will be governed by the final adjudication of such issue.

     (i)-(j)  Not applicable.

                                       4
SIGNATURES

          Pursuant to the requirements of the Securities Act of 1933, the
Company 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 Skokie, State of Illinois, on September 22, 1999.

                                PATHOGENESIS CORPORATION

                                By           /s/ Alan R. Meyer
                                    --------------------------------------
                                                 Alan R. Meyer
                                           Executive Vice President

     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/ Alan R. Meyer        Executive Vice President, Chief      September 22, 1999
--------------------
Alan R. Meyer            Financial Officer and Director
                         (Principal Financial and
                          Accounting Officer)

Wilbur H. Gantz          Chairman, Chief Executive     )
                         Officer, President and        )
                         Director (Principal           )
                         Executive Officer)            )
                                                       )
John Gordon              Director                      )
                                                       )
                                                       )
Elizabeth M. Greetham    Director                      ) By:  /s/ Alan R. Meyer
                                                       )     -------------------
                                                       )        Alan R. Meyer
                                                       )       Attorney-in-Fact
Michael J. Montgomery    Director                      )      September 22, 1999
                                                       )
                                                       )
Arthur W. Nienhuis       Director                      )
                                                       )
                                                       )
Talat M. Othman          Director                      )
                                                       )
                                                       )
Eugene L. Step           Director                      )
                                                       )
                                                       )
James R. Tobin           Director                      )
                                                       )
                                                       )
Fred Wilpon              Director                      )

                                       5
(Being the principal executive officer, the principal financial and accounting
officer and a majority of the directors of PathoGenesis Corporation.)

ORIGINAL POWER OF ATTORNEY AUTHORIZING WILBUR H. GANTZ AND ALAN R. MEYER TO
EXECUTE THIS REGISTRATION STATEMENT FOR EACH OF MS. GREETHAM AND MESSRS. GANTZ,
GORDON, MEYER, MONTGOMERY, NIENHUIS, OTHMAN, STEP, TOBIN AND WILPON HAS BEEN
EXECUTED AND FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       6
Exhibit Index

          The following are filed as part of this registration statement.

Exhibit Number               Description of Document
--------------               -----------------------

    4.1             Composite Certificate of Incorporation of PathoGenesis
                    Corporation, as amended (incorporated reference to Exhibit
                    3.1(d) of quarterly report on Form 10-Q for the three months
                    ended March 31, 1998, File No. 0-27150).

    4.1(a)          Amended and Restated Certificate of Incorporation, as
                    amended (incorporated by reference to Exhibit 3.1 to
                    registration statement on Form S-1, Registration No. 333-
                    22297).

    4.1(b)          Certificate of Amendment of Amended and Restated Certificate
                    of Incorporation (incorporated by reference to Exhibit
                    4.1(b) to registration statement on Form S-8, Registration
                    No. 333-45571).

    4.2             By-laws of the Company, as amended through June 3, 1999
                    (incorporated by reference to Exhibit 3.2 to quarterly
                    report on Form 10-Q for the three months ended June 30,
                    1999, File No. 0-27150).

    4.3             Certificate of Designations (incorporated by reference to
                    Exhibit 4.1(b) to registration statement on Form S-8,
                    Registration No. 333-45571).

    4.4             PathoGenesis Corporation PathoGenesis Corporation 1999 Stock
                    Plan (incorporated by reference to Appendix A to
                    PathoGenesis' notice and proxy statement dated April 19,
                    1999, File No. 0-27150).

    4.4(a)          Form of Stock Option Agreement for 1999 Stock Plan
                    (incorporated by reference to Exhibit 4.10 to quarterly
                    report on Form 10-Q for the three months ended June 30,
                    1999, File No. 0-27150).

    4.5             Rights Agreement, dated as of June 25, 1997, between
                    PathoGenesis Corporation and Harris Trust and Savings Bank
                    as Rights Agent, including the form of Right Certificate as
                    Exhibit B (incorporated by reference to Exhibit 1 to current
                    report on Form 8-K filed on July 10, 1997, File No.
                    0-27150).

    4.5(a)          First Amendment, dated as of March 8, 1998, to Rights
                    Agreement between PathoGenesis Corporation and Harris Trust
                    and Savings Bank, as Rights Agent (incorporated by reference
                    to Exhibit 4.1(bb) to annual report on Form 10-K for 1997,
                    File No. 0-27150).

    4.5(b)          Amendment of Rights Plan, dated as of April 13, 1999,
                    between PathoGenesis Corporation and Harris Trust and
                    Savings Bank as Rights Agent (incorporated by reference to
                    Exhibit 4.1(bbb) to amendment to registration statement on
                    Form 8-A/A, filed on April 15, 1999, File No. 0-27150).

    5               Opinion of Bell, Boyd & Lloyd.

   23.1             Consent of KPMG LLP.

   23.2             Consent of Bell, Boyd & Lloyd (included in Exhibit 5).

   24               Power of Attorney