SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549


                                   Form 8-A


               For Registration of Certain Classes of Securities
                    Pursuant to Section 12(b) or (g) of the
                        Securities Exchange Act of 1934


                            VIROPHARMA INCORPORATED
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            (Exact name of registrant as specified in its charter)


          Delaware                                        23-2789550
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         (State or other                                (IRS Employer
         jurisdiction of                                Identification No.)
         incorporation or
         organization)
 
         405 Eagleview Boulevard
              Exton, PA                                        19341
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         (Address of principal executive offices)            (Zip Code)

     If this form relates to                 If this form relates to      
     the registration of a                   the registration of a           
     class of securities                     class of securities            
     pursuant to Section                     pursuant to Section            
     12(b) of the Exchange                   12(g) of the Exchange           
     Act and is effective                    Act and is effective           
     pursuant to General                     pursuant to General            
     Instruction A.(c),                      Instruction A.(d),             
     please check the                        please check the               
     following box. [_]                      following box. [X]              

Securities Act registration statement file number to which this form 
 relates:      None 
          ---------------
          (If applicable) 

    Securities to be registered pursuant to Section 12(b) of the Act:    None
                                                                      ----------
 
          Securities to be registered pursuant to Section 12(g) of the Act:

                       Preferred Share Purchase Rights 
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                               (Title of Class)

 
Item 1. Description of Registrant's Securities to be Registered.
        ------------------------------------------------------- 

          On September 10, 1998, the Board of Directors of ViroPharma
Incorporated (the "Company") declared a dividend distribution of one Right for
each outstanding share of Common Stock, $.002 par value (each, a "Common
Share"), of the Company to stockholders of record at the close of business on
September 17, 1998.  Each Right entitles the registered holder to purchase from
the Company a unit consisting of one one-hundredth of a share (a "Unit") of the
Series A Junior Participating Preferred Shares, par value $.001 per share, of
the Company (the "Preferred Shares"), or a combination of securities and assets
of equivalent value, at a Purchase Price of $125 per Unit, subject to
adjustment.  The description and terms of the Rights are set forth in a Rights
Agreement (the "Rights Agreement") between the Company and StockTrans, Inc., as
Rights Agent.

          Initially, ownership of the Rights will be evidenced by the Common
Share certificates representing shares then outstanding, and no separate Rights
Certificates will be distributed.  The Rights will separate from the Common
Shares and a Distribution Date will occur upon the earlier of (i) 10 days
following a public announcement that a person or group of affiliated or
associated persons (an "Acquiring Person") has acquired, or obtained the right
to acquire, beneficial ownership of 20% or more of the outstanding Common Shares
(the "Stock Acquisition Date"), or (ii) the close of business on such date as
may be fixed by the Board of Directors, which date shall not be more than 65
days following the commencement of a tender offer or exchange offer that would
result in a person or group beneficially owning 20% or more of the outstanding
Common Shares.  Until the Distribution Date, (i) the Rights will be evidenced by
the Common Share certificates and will be transferred with and only with such
Common Share certificates, (ii) new Common Share certificates issued after
September 10, 1998 will contain a notation incorporating the Rights Agreement by
reference and (iii) the surrender for transfer of any certificates for Common
Shares outstanding will also constitute the transfer of the Rights associated
with the Common Shares represented by such certificate.

          The Rights are not exercisable until the Distribution Date and will
expire at the close of business on September 10, 2008, unless earlier redeemed
by the Company as described below or unless a transaction under Section 13(d) of
the Rights Agreement has occurred.

          As soon as practicable after the Distribution Date, Rights
Certificates will be mailed to holders of record of the Common Shares as of the
close of business on the Distribution Date and, thereafter, the separate Rights
Certificates alone will represent the Rights.  Except as otherwise determined by
the Board of Directors, and except in connection with the exercise of employee
stock options or stock appreciation rights or under any other benefit plan for
employees or directors or in connection with the exercise of warrants or
conversion of convertible securities, only Common Shares issued after September
10, 1998 and prior to the Distribution Date will be issued with Rights.

                                      -2-

 
          Except in the circumstances described below, after the Distribution
Date each Right will be exercisable for one one-hundredth of a Preferred Share
(a "Preferred Share Fraction").  Each Preferred Share Fraction carries voting
and dividend rights that are intended to produce the equivalent of one Common
Share.  The voting and dividend rights of the Preferred Shares are subject to
adjustment in the event of dividends, subdivisions and combinations with respect
to the Common Shares of the Company.  In lieu of issuing certificates for
Preferred Share Fractions which are less than an integral multiple of one
Preferred Share (i.e., 100 Preferred Share Fractions), the Company may pay cash
representing the current market value of the Preferred Share Fractions.

          In the event that at any time following the Stock Acquisition Date,
(i) the Company is the surviving corporation in a merger with an Acquiring
Person and its Common Shares remain outstanding, (ii) a Person becomes the
beneficial owner of more than 20% of the then outstanding Common Shares other
than pursuant to a tender offer that provides fair value to all stockholders,
(iii) an Acquiring Person engages in one or more "self-dealing" transactions as
set forth in the Rights Agreement, or (iv) during such time as there is an
Acquiring Person an event occurs that results in such Acquiring Person's
ownership interest being increased by more than 1% (e.g., a reverse stock
split), each holder of a Right will thereafter have the right to receive, upon
exercise, Common Shares (or, in certain circumstances, cash, property or other
securities of the Company) having a value equal to two times the exercise price
of the Right.  In lieu of requiring payment of the Purchase Price upon exercise
of the Rights following any such event, the Company may permit the holders
simply to surrender the Rights, in which event they will be entitled to receive
Common Shares (and other property, as the case may be) with a value of 50% of
what could be purchased by payment of the full Purchase Price.  Notwithstanding
any of the foregoing, following the occurrence of any of the events set forth in
clauses (i), (ii), (iii) or (iv) of this paragraph, all Rights that are, or
(under certain circumstances specified in the Rights Agreement) were,
beneficially owned by any Acquiring Person who was involved in the transaction
giving rise to any such event will be null and void.  However, Rights are not
exercisable following the occurrence of any of the events set forth above until
such time as the Rights are no longer redeemable by the Company as set forth
below.

          For example, at an exercise price of $125 per Right, each Right not
otherwise voided following an event set forth in the preceding paragraph would
entitle its holder to purchase $250 worth of Common Shares (or other
consideration, as noted above) for $125. Assuming that the Common Shares had a
per share value of $25 at such time, the holder of each valid Right would be
entitled to purchase ten Common Shares for $125.  Alternatively, the Company
could permit the holder to surrender each Right in exchange for stock or cash
equivalent to five Common Shares (with a value of $125) without the payment of
any consideration other than the surrender of the Right.

          In the event that, at any time following the Stock Acquisition Date,
(i) the Company is acquired in a merger or other business combination
transaction in which the

                                      -3-

 
Company is not the surviving corporation (other than a merger that is described
in, or that follows a tender offer or exchange offer described in, the second
preceding paragraph), or (ii) 50% or more of the Company's assets or earning
power is sold or transferred, each holder of a Right (except Rights that
previously have been voided as set forth above) shall thereafter have the right
to receive, upon exercise, common shares of the acquiring company having a value
equal to two times the exercise price of the Right. Again, provision is made to
permit surrender of the Rights in exchange for one-half of the value otherwise
purchasable. The events set forth in this paragraph and in the second preceding
paragraph are referred to as the "Triggering Events."

          The Purchase Price payable and the number of Units of Preferred Shares
or other securities or property issuable upon exercise of the Rights are subject
to adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Shares, (ii) if holders of the Preferred Shares are granted certain rights or
warrants to subscribe for Preferred Shares or convertible securities at less
than the current market price of the Preferred Shares, or (iii) upon the
distribution to holders of the Preferred Shares of evidences of indebtedness or
assets (excluding regular quarterly dividends) or of subscription rights or
warrants (other than those referred to above).

          With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments amount to at least 1% of the Purchase
Price.  No fractional Units will be issued and, in lieu thereof, an adjustment
in cash will be made based on the market price of the Preferred Shares on the
last trading date prior to the date of exercise.

          At any time until ten days following the Stock Acquisition Date, the
Company may redeem the Rights in whole, but not in part, at a price of $.01 per
Right.  That ten-day redemption period may be extended by the Board of Directors
so long as the Rights are still redeemable.  Immediately upon the action of the
Board of Directors ordering redemption of the Rights, the Rights will terminate
and the only right of the holders of Rights will be to receive the $.01
redemption price.

          Until a Right is exercised, the holder thereof, as such, will have no
rights as a stockholder of the Company, including, without limitation, the right
to vote or to receive dividends.  While the distribution of the Rights will not
be taxable to stockholders or to the Company, stockholders may, depending upon
the circumstances, recognize taxable income in the event that the Rights become
exercisable for Preferred Shares (or other consideration) of the Company or for
common shares of the acquiring company as set forth above.

          Other than those provisions relating to the principal economic terms
of the Rights, any of the provisions of the Rights Agreement may be amended by
the Board of Directors of the Company prior to the Distribution Date.  After the
Distribution Date, the provisions of the Rights Agreement may be amended by the
Board in order to cure any 

                                      -4-

 
ambiguity, to make changes that do not adversely affect the interests of holders
of Rights (excluding the interests of any Acquiring Person), or to shorten or
lengthen any time period under the Rights Agreement; provided, however, that no
amendment to adjust the time period governing redemption shall be made at such
time as the Rights are not redeemable.

          This summary description of the Rights does not purport to be complete
and is qualified in its entirety by reference to the Rights Agreement, which is
filed as an Exhibit to the Company's Current Report on Form 8-K dated September
10, 1998.


Item 2.  Exhibits.
         -------- 

        1.    Rights Agreement, dated as of September 10, 1998, between
              ViroPharma Incorporated and StockTrans, Inc., as Rights Agent
              (incorporated herein by reference to Exhibit 4 to the Registrant's
              Current Report on Form 8-K dated September 10, 1998).

                                      -5-

 
                                   SIGNATURE


          Pursuant to the requirements of Section 12 of the Securities Exchange
Act of 1934, the registrant has duly caused this registration statement to be
signed on its behalf by the undersigned, thereunto duly authorized.


                                     VIROPHARMA INCORPORATED
                          
                          
                          
                                     By:   /s/ Claude H. Nash
                                          -----------------------------
                                          Name:  Claude H. Nash
                                          Title:  President and CEO


Dated:  September 16, 1998

 
 

                                      -6-

 
                                 EXHIBIT INDEX
                                 -------------

Exhibit
Number                            Description
- ------                            ----------- 

       1.     Rights Agreement, dated as of September 10, 1998,
              between ViroPharma Incorporated and StockTrans, Inc.,
              as Rights Agent (incorporated herein by reference to
              Exhibit 4 to the Registrant's Current Report on Form 8-K
              dated September 10, 1998).

                                      -7-