<PAGE>   1
As filed with the Securities and Exchange Commission on May 15, 1998
                                                   Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549



                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                                   ----------

                               PHARMACYCLICS, INC.
             (Exact name of registrant as specified in its charter)

              DELAWARE                                    94-3148201
    (State or other jurisdiction               (IRS Employer Identification No.)
  of incorporation or organization)

                             995 EAST ARQUES AVENUE
                           SUNNYVALE, CALIFORNIA 94086
               (Address of principal executive offices) (Zip Code)

                                   ----------

                               PHARMACYCLICS, INC.
                             1995 STOCK OPTION PLAN
                          EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the Plan)

                                   ----------

                             RICHARD A. MILLER, M.D.
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               PHARMACYCLICS, INC.
                   995 EAST ARQUES AVENUE, SUNNYVALE, CA 94086
                     (Name and address of agent for service)
                                 (408) 774-0330
          (Telephone number, including area code, of agent for service)

                                   ----------

               This Registration Statement shall become effective
                 immediately upon filing with the Securities and
                      Exchange Commission and sales of the
                   registered securities will begin as soon as
                        reasonably practicable after such
                                 effective date.

                                   ----------

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>

                                          Amount to be           Offering Price         Aggregate Offering          Amount of
Title of Securities to be Registered      Registered(1)             per Share                 Price            Registration Fee(2)
==================================================================================================================================
<S>                                     <C>                            <C>             <C>                        <C>      
1995 Stock Option Plan 
  Common Stock                            602,042 shares             $32.94              $19,831,263.48             $5,850.22

Employee Stock Purchase Plan 
  Common Stock                             50,000 shares             $32.94              $ 1,647,000                $  485.87

                                                                                        Aggregate Filing Fee: 6,336.09
==================================================================================================================================
</TABLE>

(1)  This Registration Statement shall also cover any additional shares of
     Registrant's Common Stock which become issuable under the 1995 Stock Option
     Plan and Employee Stock Purchase Plan by reason of any stock dividend,
     stock split, recapitalization or other similar transaction effected without
     the Registrant's receipt of consideration which results in an increase in
     the number of the outstanding shares of Registrant's Common Stock.


<PAGE>   2



(2)  Calculated solely for purposes of this offering under Rule 457(h) of the
     Securities Act of 1933, as amended, on the basis of the average of the high
     and low selling prices per share of Registrant's Common Stock on May 11,
     1998 as reported by the Nasdaq National Market.


<PAGE>   3



                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.           Incorporation of Documents by Reference

                  The Registrant hereby incorporates by reference into this
Registration Statement the following documents previously filed with the
Securities and Exchange Commission ("SEC"):

                  (a)      The Registrant's Annual Report on Form 10-K for the
                           fiscal year ended June 30, 1997, filed with the SEC
                           on September 24, 1997;

                  (b)      The Registrant's Quarterly Reports on Form 10-Q for
                           the periods ending September 30, 1997, December 31,
                           1997 and March 31, 1998 filed with the SEC on
                           November 13, 1997, February 17, 1998 and May 14,
                           1998, respectively, and

                  (c)      The Registrant's Registration Statement No. 00-27066
                           on Form 8-A filed with the SEC on October 20, 1995
                           pursuant to Section 12 of the Securities Exchange Act
                           of 1934 (the "1934 Act"), which describes the terms,
                           rights and provisions applicable to the Registrant's
                           outstanding Common Stock.

                  All reports and definitive proxy or information statements
filed pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act after the
date of this Registration Statement and prior to the filing of a post-effective
amendment which indicates that all securities offered hereby have been sold or
which deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference into this Registration Statement and to be a part
hereof from the date of filing of such documents. Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any subsequently filed
document which also is deemed to be incorporated by reference herein modifies or
supersedes such statement.


Item 4.           Description of Securities

                  Not Applicable.


Item 5.           Interests of Named Experts and Counsel

                  Not Applicable.


Item 6.           Indemnification of Directors and Officers

                  Under Section 145 of the Delaware General Corporation Law, the
Registrant has broad powers to indemnify its directors and officers against
liabilities they may incur in such capacities, including liabilities under the
Securities Act of 1933, as amended (the "1933 Act"). The Registrant's Bylaws
(the "Bylaws") provide that the Registrant shall indemnify its directors and
officers if such officer or director acted (i) in good faith, (ii) in a manner
reasonably believed to be in or not opposed to the best interests of the
Registrant, and (iii) with respect to any criminal action or proceeding, had no
reasonable cause to believe such conduct was unlawful. The Registrant believes
that indemnification under its Bylaws covers at least negligence and gross
negligence, and requires the Registrant to advance litigation expenses in the
case of stockholder derivative actions or other actions, against an undertaking
by the directors and officers to repay such advances if it is ultimately
determined that the director is not entitled to indemnification. The Bylaws
further provide that rights conferred under such Bylaws shall not be deemed to
be exclusive of any other right such persons may have or acquire under any
agreement, vote of stockholders or disinterested directors, or otherwise.


                                      II-1
<PAGE>   4
                  In addition, the Registrant's Certificate of Incorporation
(the "Certificate of Incorporation") provides that, pursuant to Delaware law,
none of its directors shall be liable for monetary damages for breach of his or
her fiduciary duty of care to the Registrant and its stockholders. This
provision in the Certificate of Incorporation does not eliminate the duty of
care, and in appropriate circumstances equitable remedies such as injunctive or
other forms of non-monetary relief will remain available under Delaware law. In
addition, each director will continue to be subject to liability for breach of
the director's duty of loyalty to the Registrant for acts or omissions not in
good faith or involving intentional misconduct, for knowing violations of law,
for actions leading to improper personal benefit to the director, and for
payment of dividends or approval of stock repurchases or redemptions that are
unlawful under Delaware law. The provision also does not affect a director's
responsibilities under any other law, such as the federal securities laws or
state or federal environmental laws. The Certificate of Incorporation further
provides that the Registrant shall indemnify its directors and officers to the
fullest extent permitted by law and requires the Registrant to advance
litigation expenses in the case of stockholder derivative actions or other
actions, against an undertaking by the director to repay such advances if it is
ultimately determined that the director is not entitled to indemnification. The
Certificate of Incorporation also provides that rights conferred under such
Certificate of Incorporation shall not be deemed to be exclusive of any other
right such persons may have or acquire under any statute, the Certificate of
Incorporation, the Bylaws, agreement, vote of stockholders or disinterested
directors, or otherwise.

                  The Registrant has obtained a liability insurance policy for
the officers and directors that, subject to certain limitations, terms and
conditions, will insure them against losses arising from wrongful acts (as
defined by the policy) in their capacity as directors or officers.

                  In addition, the Registrant has entered into agreements to
indemnify its directors and certain of its officers in addition to the
indemnification provided for in the Certificate of Incorporation and Bylaws.
These agreements, among other things, indemnify the Registrant's directors and
certain of its officers for certain expenses (including attorneys fees),
judgments, fines and settlement amounts incurred by such person in any action or
proceeding, including any action by or in the right of the Registrant, on
account of services as a director or officer of the Registrant or as a director
or officer of any subsidiary of the Registrant, or as a director or officer of
any other company or enterprise that the person provides services to at the
request of the Registrant.


Item 7.           Exemption from Registration Claimed

                  Not Applicable.

Item 8.           Exhibits

<TABLE>
<CAPTION>
Exhibit Number        Exhibit
--------------        -------
<S>                   <C>                                    
      4               Instruments Defining the Rights of Stockholders. Reference
                      is made to Registrant's Registration Statement No.
                      00-27066 on Form 8-A, which is incorporated herein by
                      reference pursuant to Item 3(c).

      5               Opinion and consent of Brobeck, Phleger & Harrison LLP.

     23.1             Consent of Price Waterhouse LLP - Independent Accountants.

     23.2             Consent of Brobeck, Phleger & Harrison LLP is contained in
                      Exhibit 5.

     24               Power of Attorney. Reference is made to page II-4 of this
                      Registration Statement.

     99.1             1995 Stock Option Plan.

     99.2*            Form of Notice of Grant of Stock Option generally to be
                      used under the 1995 Stock Option Plan.

     99.3             Form of Stock Option Agreement.

     99.4             Form of Addendum to Stock Option Agreement (Limited Stock
                      Appreciation Right).
</TABLE>

                                      II-2


<PAGE>   5


<TABLE>

<S>                   <C> 
     99.5*            Form of Addendum to Stock Option Agreement (Special Tax
                      Election).

     99.6*            Form of Addendum to Stock Option Agreement (Involuntary
                      Termination Following Change in Control).

     99.7             Form of Employee Stock Purchase Plan.

     99.8*            Form of Employee Stock Purchase Plan Enrollment/Change
                      Form.

     99.9*            Form of Stock Purchase Agreement.
</TABLE>

    * Exhibits 99.2, 99.5, 99.6, 99.8 and 99.9 are incorporated herein by
reference to Exhibits 99.2, 99.5, 99.6, 99.12 and 99.13, respectively, of
Registrant's Registration Statement No. 33-98514 on Form S-8 which was filed
with the SEC on October 23, 1995.


Item 9.               Undertakings

                      A. 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 (i) to include any
prospectus required by Section 10(a)(3) of the 1933 Act, (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 and (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 clauses
(1)(i) and (1)(ii) shall 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 Registrant pursuant to Section 13 or Section 15(d) of the 1934 Act
that are incorporated by reference into this Registration Statement; (2) that
for the purpose of determining any liability under the 1933 Act 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 and
(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
Registrant's 1995 Stock Option Plan.

                      B. The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the 1933 Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
1934 Act that is incorporated by reference into 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. Insofar as indemnification for liabilities arising
under the 1933 Act may be permitted to directors, officers or controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that, in the opinion of the SEC, such
indemnification is against public policy as expressed in the 1933 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 1933 Act and will be governed by the final
adjudication of such issue.

                                      II-3



<PAGE>   6
                                   SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, 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 Sunnyvale, State of California, on
this 14th day of May, 1998.

                                      PHARMACYCLICS, INC.


                                      By:  /s/Richard A. Miller, M.D.
                                           -------------------------------------
                                           Richard A. Miller, M.D.
                                           President, Chief Executive Officer 
                                           and Director

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

         That the undersigned officers and directors of Pharmacyclics, Inc., a
Delaware corporation, do hereby constitute and appoint Richard A. Miller, M.D.
and Marc L. Steuer and each of them, the lawful attorneys-in-fact and agents
with full power and authority to do any and all acts and things and to execute
any and all instruments which said attorneys and agents, and any one of them,
determine may be necessary or advisable or required to enable said corporation
to comply with the Securities Act of 1933, as amended, and any rules or
regulations or requirements of the Securities and Exchange Commission in
connection with this Registration Statement. Without limiting the generality of
the foregoing power and authority, the powers granted include the power and
authority to sign the names of the undersigned officers and directors in the
capacities indicated below to this Registration Statement, to any and all
amendments, both pre-effective and post-effective, and supplements to this
Registration Statement, and to any and all instruments or documents filed as
part of or in conjunction with this Registration Statement or amendments or
supplements thereof, and each of the undersigned hereby ratifies and confirms
that all said attorneys and agents, or any one of them, shall do or cause to be
done by virtue hereof. This Power of Attorney may be signed in several
counterparts.

                  IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed below by the following
persons in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
Signature                            Title                                   Date
---------                            -----                                   ----
<S>                                 <C>                                 <C>

/s/ Richard A. Miller, M.D          President, Chief Executive           May 14, 1998
-----------------------------       Officer and Director (Principal
Richard A. Miller, M.D.             Executive Officer)
                                     



/s/ Marc L. Steuer                  Vice President Business              May 14, 1998
------------------------------      Development
Marc L. Steuer                       
</TABLE>



                                      II-4


<PAGE>   7




<TABLE>
<CAPTION>
Signature                            Title                                   Date
---------                            -----                                   ----
<S>                                 <C>                                  <C>

  /s/Leiv Lea                        Vice President, Finance             May 14, 1998
---------------------------------    and Administration and Chief  
Leiv Lea                             Financial Officer (Principal
                                     Financial and Accounting Officer)


  /s/Thomas D. Kiley                 Director                            May 14, 1998
---------------------------------
Thomas D. Kiley




  /s/Joseph S. Lacob                 Director                            May 14, 1998
---------------------------------
Joseph S. Lacob




  /s/Craig C. Taylor                 Director                            May 14, 1998
---------------------------------
Craig C. Taylor




                                     Director                            May   , 1998
---------------------------------
Joseph C. Scodari




  /s/Brian A. Markison               Director                            May 14, 1998
---------------------------------
Brian A. Markison
</TABLE>



                                      II-5


<PAGE>   8
                                  EXHIBIT INDEX
<TABLE>
<CAPTION>

Exhibit
Number                Exhibit
------                -------
<S>                   <C>                                    
      4               Instruments Defining the Rights of Stockholders. Reference
                      is made to Registrant's Registration Statement No.
                      00-27066 on Form 8-A, which is incorporated herein by
                      reference pursuant to Item 3(c).

      5               Opinion and consent of Brobeck, Phleger & Harrison LLP.

     23.1             Consent of Price Waterhouse LLP - Independent Accountants.

     23.2             Consent of Brobeck, Phleger & Harrison LLP is contained in
                      Exhibit 5.

     24               Power of Attorney. Reference is made to page II-4 of this
                      Registration Statement.

     99.1             1995 Stock Option Plan.

     99.2*            Form of Notice of Grant of Stock Option generally to be
                      used under the 1995 Stock Option Plan.

     99.3             Form of Stock Option Agreement.

     99.4             Form of Addendum to Stock Option Agreement (Limited Stock
                      Appreciation Right).

     99.5*            Form of Addendum to Stock Option Agreement (Special Tax
                      Election).

     99.6*            Form of Addendum to Stock Option Agreement (Involuntary
                      Termination Following Change in Control).

     99.7             Form of Employee Stock Purchase Plan.

     99.8*            Form of Employee Stock Purchase Plan Enrollment/Change
                      Form.

     99.9*            Form of Stock Purchase Agreement.
</TABLE>

    * Exhibits 99.2, 99.5, 99.6, 99.8 and 99.9 are incorporated herein by
reference to Exhibits 99.2, 99.5, 99.6, 99.12 and 99.13, respectively, of
Registrant's Registration Statement No. 33-98514 on Form S-8 which was filed
with the SEC on October 23, 1995.
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 23347}]
{"company-data": {"conformed-name": "PHARMACYCLICS INC", "cik": "0000949699", "assigned-sic": "2834", "irs-number": "943148201", "state-of-incorporation": "DE", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-52881", "film-number": "98626495"}, "business-address": {"street1": "995 EAST ARQUES AVE", "city": "SUNNYVALE", "state": "CA", "zip": "94086", "phone": "4087743345"}, "mail-address": {"street1": "995 EAST ARQUES AVENUE", "city": "SUNNYVALE", "state": "CA", "zip": "94086"}}
1
As filed with the Securities and Exchange Commission on May 15, 1998
                                                   Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                                   ----------

                               PHARMACYCLICS, INC.
             (Exact name of registrant as specified in its charter)

              DELAWARE                                    94-3148201
    (State or other jurisdiction               (IRS Employer Identification No.)
  of incorporation or organization)

                             995 EAST ARQUES AVENUE
                           SUNNYVALE, CALIFORNIA 94086
               (Address of principal executive offices) (Zip Code)

                                   ----------

                               PHARMACYCLICS, INC.
                             1995 STOCK OPTION PLAN
                          EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the Plan)

                                   ----------

                             RICHARD A. MILLER, M.D.
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               PHARMACYCLICS, INC.
                   995 EAST ARQUES AVENUE, SUNNYVALE, CA 94086
                     (Name and address of agent for service)
                                 (408) 774-0330
          (Telephone number, including area code, of agent for service)

                                   ----------

               This Registration Statement shall become effective
                 immediately upon filing with the Securities and
                      Exchange Commission and sales of the
                   registered securities will begin as soon as
                        reasonably practicable after such
                                 effective date.

                                   ----------

                         CALCULATION OF REGISTRATION FEE
Amount to be           Offering Price         Aggregate Offering          Amount of
Title of Securities to be Registered      Registered(1)             per Share                 Price            Registration Fee(2)
==================================================================================================================================
1995 Stock Option Plan 
  Common Stock                            602,042 shares             $32.94              $19,831,263.48             $5,850.22

Employee Stock Purchase Plan 
  Common Stock                             50,000 shares             $32.94              $ 1,647,000                $  485.87

                                                                                        Aggregate Filing Fee: 6,336.09
==================================================================================================================================
(1)  This Registration Statement shall also cover any additional shares of
     Registrant's Common Stock which become issuable under the 1995 Stock Option
     Plan and Employee Stock Purchase Plan by reason of any stock dividend,
     stock split, recapitalization or other similar transaction effected without
     the Registrant's receipt of consideration which results in an increase in
     the number of the outstanding shares of Registrant's Common Stock.
2

(2)  Calculated solely for purposes of this offering under Rule 457(h) of the
     Securities Act of 1933, as amended, on the basis of the average of the high
     and low selling prices per share of Registrant's Common Stock on May 11,
     1998 as reported by the Nasdaq National Market.
3

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.           Incorporation of Documents by Reference

                  The Registrant hereby incorporates by reference into this
Registration Statement the following documents previously filed with the
Securities and Exchange Commission ("SEC"):

                  (a)      The Registrant's Annual Report on Form 10-K for the
                           fiscal year ended June 30, 1997, filed with the SEC
                           on September 24, 1997;

                  (b)      The Registrant's Quarterly Reports on Form 10-Q for
                           the periods ending September 30, 1997, December 31,
                           1997 and March 31, 1998 filed with the SEC on
                           November 13, 1997, February 17, 1998 and May 14,
                           1998, respectively, and

                  (c)      The Registrant's Registration Statement No. 00-27066
                           on Form 8-A filed with the SEC on October 20, 1995
                           pursuant to Section 12 of the Securities Exchange Act
                           of 1934 (the "1934 Act"), which describes the terms,
                           rights and provisions applicable to the Registrant's
                           outstanding Common Stock.

                  All reports and definitive proxy or information statements
filed pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act after the
date of this Registration Statement and prior to the filing of a post-effective
amendment which indicates that all securities offered hereby have been sold or
which deregisters all securities then remaining unsold shall be deemed to be
incorporated by reference into this Registration Statement and to be a part
hereof from the date of filing of such documents. Any statement contained in a
document incorporated or deemed to be incorporated by reference herein shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any subsequently filed
document which also is deemed to be incorporated by reference herein modifies or
supersedes such statement.

Item 4.           Description of Securities

                  Not Applicable.

Item 5.           Interests of Named Experts and Counsel

                  Not Applicable.

Item 6.           Indemnification of Directors and Officers

                  Under Section 145 of the Delaware General Corporation Law, the
Registrant has broad powers to indemnify its directors and officers against
liabilities they may incur in such capacities, including liabilities under the
Securities Act of 1933, as amended (the "1933 Act"). The Registrant's Bylaws
(the "Bylaws") provide that the Registrant shall indemnify its directors and
officers if such officer or director acted (i) in good faith, (ii) in a manner
reasonably believed to be in or not opposed to the best interests of the
Registrant, and (iii) with respect to any criminal action or proceeding, had no
reasonable cause to believe such conduct was unlawful. The Registrant believes
that indemnification under its Bylaws covers at least negligence and gross
negligence, and requires the Registrant to advance litigation expenses in the
case of stockholder derivative actions or other actions, against an undertaking
by the directors and officers to repay such advances if it is ultimately
determined that the director is not entitled to indemnification. The Bylaws
further provide that rights conferred under such Bylaws shall not be deemed to
be exclusive of any other right such persons may have or acquire under any
agreement, vote of stockholders or disinterested directors, or otherwise.

                                      II-1
4
                  In addition, the Registrant's Certificate of Incorporation
(the "Certificate of Incorporation") provides that, pursuant to Delaware law,
none of its directors shall be liable for monetary damages for breach of his or
her fiduciary duty of care to the Registrant and its stockholders. This
provision in the Certificate of Incorporation does not eliminate the duty of
care, and in appropriate circumstances equitable remedies such as injunctive or
other forms of non-monetary relief will remain available under Delaware law. In
addition, each director will continue to be subject to liability for breach of
the director's duty of loyalty to the Registrant for acts or omissions not in
good faith or involving intentional misconduct, for knowing violations of law,
for actions leading to improper personal benefit to the director, and for
payment of dividends or approval of stock repurchases or redemptions that are
unlawful under Delaware law. The provision also does not affect a director's
responsibilities under any other law, such as the federal securities laws or
state or federal environmental laws. The Certificate of Incorporation further
provides that the Registrant shall indemnify its directors and officers to the
fullest extent permitted by law and requires the Registrant to advance
litigation expenses in the case of stockholder derivative actions or other
actions, against an undertaking by the director to repay such advances if it is
ultimately determined that the director is not entitled to indemnification. The
Certificate of Incorporation also provides that rights conferred under such
Certificate of Incorporation shall not be deemed to be exclusive of any other
right such persons may have or acquire under any statute, the Certificate of
Incorporation, the Bylaws, agreement, vote of stockholders or disinterested
directors, or otherwise.

                  The Registrant has obtained a liability insurance policy for
the officers and directors that, subject to certain limitations, terms and
conditions, will insure them against losses arising from wrongful acts (as
defined by the policy) in their capacity as directors or officers.

                  In addition, the Registrant has entered into agreements to
indemnify its directors and certain of its officers in addition to the
indemnification provided for in the Certificate of Incorporation and Bylaws.
These agreements, among other things, indemnify the Registrant's directors and
certain of its officers for certain expenses (including attorneys fees),
judgments, fines and settlement amounts incurred by such person in any action or
proceeding, including any action by or in the right of the Registrant, on
account of services as a director or officer of the Registrant or as a director
or officer of any subsidiary of the Registrant, or as a director or officer of
any other company or enterprise that the person provides services to at the
request of the Registrant.

Item 7.           Exemption from Registration Claimed

                  Not Applicable.

Item 8.           Exhibits
Exhibit Number        Exhibit
--------------        -------
4               Instruments Defining the Rights of Stockholders. Reference
                      is made to Registrant's Registration Statement No.
                      00-27066 on Form 8-A, which is incorporated herein by
                      reference pursuant to Item 3(c).

      5               Opinion and consent of Brobeck, Phleger & Harrison LLP.

     23.1             Consent of Price Waterhouse LLP - Independent Accountants.

     23.2             Consent of Brobeck, Phleger & Harrison LLP is contained in
                      Exhibit 5.

     24               Power of Attorney. Reference is made to page II-4 of this
                      Registration Statement.

     99.1             1995 Stock Option Plan.

     99.2*            Form of Notice of Grant of Stock Option generally to be
                      used under the 1995 Stock Option Plan.

     99.3             Form of Stock Option Agreement.

     99.4             Form of Addendum to Stock Option Agreement (Limited Stock
                      Appreciation Right).
II-2
5
99.5*            Form of Addendum to Stock Option Agreement (Special Tax
                      Election).

     99.6*            Form of Addendum to Stock Option Agreement (Involuntary
                      Termination Following Change in Control).

     99.7             Form of Employee Stock Purchase Plan.

     99.8*            Form of Employee Stock Purchase Plan Enrollment/Change
                      Form.

     99.9*            Form of Stock Purchase Agreement.
* Exhibits 99.2, 99.5, 99.6, 99.8 and 99.9 are incorporated herein by
reference to Exhibits 99.2, 99.5, 99.6, 99.12 and 99.13, respectively, of
Registrant's Registration Statement No. 33-98514 on Form S-8 which was filed
with the SEC on October 23, 1995.

Item 9.               Undertakings

                      A. 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 (i) to include any
prospectus required by Section 10(a)(3) of the 1933 Act, (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 and (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 clauses
(1)(i) and (1)(ii) shall 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 Registrant pursuant to Section 13 or Section 15(d) of the 1934 Act
that are incorporated by reference into this Registration Statement; (2) that
for the purpose of determining any liability under the 1933 Act 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 and
(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
Registrant's 1995 Stock Option Plan.

                      B. The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the 1933 Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
1934 Act that is incorporated by reference into 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. Insofar as indemnification for liabilities arising
under the 1933 Act may be permitted to directors, officers or controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that, in the opinion of the SEC, such
indemnification is against public policy as expressed in the 1933 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 1933 Act and will be governed by the final
adjudication of such issue.

                                      II-3
6
                                   SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, 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 Sunnyvale, State of California, on
this 14th day of May, 1998.

                                      PHARMACYCLICS, INC.

                                      By:  /s/Richard A. Miller, M.D.
                                           -------------------------------------
                                           Richard A. Miller, M.D.
                                           President, Chief Executive Officer 
                                           and Director

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

         That the undersigned officers and directors of Pharmacyclics, Inc., a
Delaware corporation, do hereby constitute and appoint Richard A. Miller, M.D.
and Marc L. Steuer and each of them, the lawful attorneys-in-fact and agents
with full power and authority to do any and all acts and things and to execute
any and all instruments which said attorneys and agents, and any one of them,
determine may be necessary or advisable or required to enable said corporation
to comply with the Securities Act of 1933, as amended, and any rules or
regulations or requirements of the Securities and Exchange Commission in
connection with this Registration Statement. Without limiting the generality of
the foregoing power and authority, the powers granted include the power and
authority to sign the names of the undersigned officers and directors in the
capacities indicated below to this Registration Statement, to any and all
amendments, both pre-effective and post-effective, and supplements to this
Registration Statement, and to any and all instruments or documents filed as
part of or in conjunction with this Registration Statement or amendments or
supplements thereof, and each of the undersigned hereby ratifies and confirms
that all said attorneys and agents, or any one of them, shall do or cause to be
done by virtue hereof. This Power of Attorney may be signed in several
counterparts.

                  IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed below by the following
persons in the capacities and on the dates indicated.
Signature                            Title                                   Date
---------                            -----                                   ----
/s/ Richard A. Miller, M.D          President, Chief Executive           May 14, 1998
-----------------------------       Officer and Director (Principal
Richard A. Miller, M.D.             Executive Officer)
                                     

/s/ Marc L. Steuer                  Vice President Business              May 14, 1998
------------------------------      Development
Marc L. Steuer
II-4
7
Signature                            Title                                   Date
---------                            -----                                   ----
/s/Leiv Lea                        Vice President, Finance             May 14, 1998
---------------------------------    and Administration and Chief  
Leiv Lea                             Financial Officer (Principal
                                     Financial and Accounting Officer)

  /s/Thomas D. Kiley                 Director                            May 14, 1998
---------------------------------
Thomas D. Kiley

  /s/Joseph S. Lacob                 Director                            May 14, 1998
---------------------------------
Joseph S. Lacob

  /s/Craig C. Taylor                 Director                            May 14, 1998
---------------------------------
Craig C. Taylor

                                     Director                            May   , 1998
---------------------------------
Joseph C. Scodari

  /s/Brian A. Markison               Director                            May 14, 1998
---------------------------------
Brian A. Markison
II-5
8
                                  EXHIBIT INDEX
Exhibit
Number                Exhibit
------                -------
4               Instruments Defining the Rights of Stockholders. Reference
                      is made to Registrant's Registration Statement No.
                      00-27066 on Form 8-A, which is incorporated herein by
                      reference pursuant to Item 3(c).

      5               Opinion and consent of Brobeck, Phleger & Harrison LLP.

     23.1             Consent of Price Waterhouse LLP - Independent Accountants.

     23.2             Consent of Brobeck, Phleger & Harrison LLP is contained in
                      Exhibit 5.

     24               Power of Attorney. Reference is made to page II-4 of this
                      Registration Statement.

     99.1             1995 Stock Option Plan.

     99.2*            Form of Notice of Grant of Stock Option generally to be
                      used under the 1995 Stock Option Plan.

     99.3             Form of Stock Option Agreement.

     99.4             Form of Addendum to Stock Option Agreement (Limited Stock
                      Appreciation Right).

     99.5*            Form of Addendum to Stock Option Agreement (Special Tax
                      Election).

     99.6*            Form of Addendum to Stock Option Agreement (Involuntary
                      Termination Following Change in Control).

     99.7             Form of Employee Stock Purchase Plan.

     99.8*            Form of Employee Stock Purchase Plan Enrollment/Change
                      Form.

     99.9*            Form of Stock Purchase Agreement.
* Exhibits 99.2, 99.5, 99.6, 99.8 and 99.9 are incorporated herein by
reference to Exhibits 99.2, 99.5, 99.6, 99.12 and 99.13, respectively, of
Registrant's Registration Statement No. 33-98514 on Form S-8 which was filed
with the SEC on October 23, 1995.