<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION

                            Washington, D.C.  02549

                          ------------------------------
  
                                   FORM 8-K

                                CURRENT REPORT
                    PURSUANT TO SECTION 13 OR 15(D) OF THE
                        SECURITIES EXCHANGE ACT OF 1934


    Date of Report (date of earliest event reported):   December 7, 1998  
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                           PRI Automation, Inc.                            
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            (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)


         Massachusetts              0-24934              04-2495703
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(STATE OR OTHER JURISDICTION)      (COMMISSION          (IRS EMPLOYER 
        OF INCORPORATION)          FILE NUMBER)       IDENTIFICATION NO.)


805 Middlesex Turnpike, Billerica, Massachusetts             01821
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(ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                   (ZIP CODE)


Registrant's telephone number, including area code:       (978) 670-4270     
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                                Not Applicable 
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         (FORMER NAME OR FORMER ADDRESS, IF CHANGED SINCE LAST REPORT)
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ITEM 5.  OTHER EVENTS.

        On December 7, 1998 the Board of Directors of PRI Automation, Inc. (the
"Company") declared a dividend of one Right for each outstanding share of Common
Stock, par value $.01 per share, of the Company (the "Common Shares"). The
Rights will be issued to the holders of record of Common Shares outstanding on
December 9, 1998, and with respect to Common Shares issued thereafter until the
Distribution Date (as defined below) and, in certain circumstances, with respect
to Common Shares issued after the Distribution Date. Each Right, when it becomes
exercisable as described below, will entitle the registered holder to purchase
from the Company one one-hundredth (1/100th) of a share of Series A
Participating Cumulative Preferred Stock, par value $.01 per share, of the
Company (the "Preferred Shares") at a price of $140 (the "Purchase Price"). The
description and terms of the Rights are set forth in a Rights Agreement dated as
of December 9, 1998 (the "Rights Agreement") between the Company and State
Street Bank and Trust Company, as Rights Agent (the "Rights Agent").

        Until the earlier of (i) the date on which the Company first publicly
announces that a person or group has (including any affiliate or associate of
such person or group) acquired, or has obtained the right to acquire, beneficial
ownership of 20% or more of the outstanding Common Shares, including Common
Shares issuable upon the exchange of any securities issued in connection with
the Company's acquisition of Promis Systems Corporation Ltd. (such person or
group being called an "Acquiring Person") or (ii) the date, if any, as may be
designated by the Board of Directors following the commencement of, or first
public disclosure of an intent to commence, a tender or exchange offer for
outstanding Common Shares which could result in the offeror becoming the
beneficial owner of 20% or more of the outstanding Common Shares, including
Common Shares issuable upon the exchange of any securities issued in connection
with the Company's acquisition of Promis Systems Corporation Ltd. (the earlier
of such dates being called the "Distribution Date"), the Rights will be
evidenced by the certificates for Common Shares registered in the names of the
holders thereof (which certificates for Common Shares shall also be deemed to be
Right Certificates, as defined below) and not by separate Right Certificates.
Therefore, until the Distribution Date, the Rights will be transferred with and
only with the Common Shares.

        As soon as practicable following the Distribution Date, separate
certificates evidencing the Rights ("Right Certificates") will be mailed to
holders of record of the Common Shares as of the close of business on the
Distribution Date (and to each initial record holder of certain Common Shares
originally issued after the Distribution Date), and such separate Right
Certificates alone will thereafter evidence the Rights. The Rights are not
exercisable until the Distribution Date and will expire on December 9, 2008 (the
"Expiration Date"), unless earlier redeemed by the Company as described below.

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       To preserve the actual or potential economic value of the Rights, the
number of Preferred Shares or other securities issuable upon exercise of a
Right, the Purchase Price and Redemption Price and the number of Rights
associated with each outstanding Common Share are all subject to adjustment by
the Board of Directors as provided in the Rights Agreement in the event of any
change in the Common Shares or Preferred Shares, whether by reason of stock
dividends, stock splits, recapitalizations, mergers, consolidations,
combinations or exchanges of securities, split-ups, split-offs, spin-offs,
liquidations or any other similar changes in capitalization, any distribution or
issuance of cash, assets, evidences of indebtedness or subscription rights,
options or warrants to holders of Common Shares or Preferred Shares, as the case
may be (other than distribution of the Rights or regular quarterly cash
dividends) or otherwise.

       The Preferred Shares are authorized to be issued in fractions which are
an integral multiple of one one-hundredth (1/100th) of a Preferred Share. The
Company may, but is not required to, issue fractions of shares upon the exercise
of Rights, and, in lieu of fractional shares, the Company may issue certificates
or utilize a depository arrangement as provided by the terms of the Preferred
Shares and, in the case of fractions other than one one-hundredth (1/100th) of a
Preferred Share or integral multiples thereof, may make a cash payment based on
the market price of such shares.

       Upon a person or a group becoming an Acquiring Person, the Rights will
entitle each holder of a Right to purchase, for the Purchase Price, that number
of one one-hundredths (1/100ths) of a Preferred Share equivalent to the number
of Common Shares which at the time of the transaction would have a market value
of twice the Purchase Price.

       In the event the Company is acquired in a merger or other business
combination or 50% or more of its assets or assets representing 50% or more of
its earning power are sold, leased, exchanged or otherwise transferred (in one
or more transactions) to a publicly traded corporation, each Right will entitle
its holder to purchase, for the Purchase Price, that number of common shares of
such corporation which at the time of the transaction would have a market value
of twice the Purchase Price. In the event the Company is acquired in a merger or
other business combination or 50% or more of its assets or assets representing
50% or more of the earning power of the Company are sold, leased, exchanged or
otherwise transferred (in one or more transactions) to an entity that is not a
publicly traded corporation, each Right will entitle its holder to purchase, for
the Purchase Price, at such holder's option, (i) that number of shares of such
entity (or, at such holder's option, of the surviving corporation in such
acquisition, which could be the Company) which at the time of the transaction
would have a book value of twice the


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Purchase Price or (ii) if such entity has an affiliate which has publicly traded
common shares, that number of common shares of such affiliate which at the time
of the transaction would have a market value of twice the Purchase Price.

       Any Rights that are at any time beneficially owned by an Acquiring 
Person (or any affiliate or associate of an Acquiring Person) shall be null and
void and nontransferable, and any holder of any such Right (including any
purported transferee or subsequent holder) shall not have any right to exercise
or transfer any such right.

       At any time after a person or a group becomes an Acquiring Person, the
Board of Directors of the Company may exchange all or part of the then
outstanding Rights (other than Rights that have become null and void and
nontransferable as described above) for consideration per Right consisting of
one-half of the securities that otherwise would have been issuable to the holder
of each Right upon exercise thereof. The Board of Directors of the Company may
also issue, in substitution for Preferred Shares, Common Shares having an
equivalent market value to the Preferred Shares if, at such time, the Company
has a sufficient number of Common Shares issued but not outstanding or
authorized but unissued.

       At any time prior to the earlier of (i) the date that a person has
become an Acquiring Person or (ii) the Expiration Date, the Board of Directors
of the Company may redeem the Rights in whole, but not in part, at a price (in
cash or Common Shares or other securities of the Company deemed by the Board of
Directors to be at least equivalent in value) of $.001 per Right (the
"Redemption Price").

       Immediately upon the action of the Board of Directors of the Company
electing to redeem the Rights, the Company shall make an announcement thereof,
and, upon such election, the right to exercise the Rights will terminate and the
only right of the holders of Rights will be to receive the Redemption Price.

       Until a Right is exercised, the holder thereof, as such, will have no
rights therefrom as a stockholder of the Company, including, without 
limitation, the right to vote or to receive dividends.

       At any time prior to the Distribution Date, the Company may, without 
the approval of any holder of the Rights, supplement or amend any provision of
the Rights Agreement (including the date on which the Distribution Date shall
occur, the time during which the Rights may be redeemed or the terms of the
Preferred Shares), except that no supplement or amendment shall be made which
reduces the Redemption Price or provides for an earlier Expiration Date.


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        The Rights have certain anti-takeover effects.  The Rights will cause
substantial dilution to a person or group that attempts to acquire the Company
without conditioning the offer on substantially all the Rights being acquired.
The Rights will not interfere with any merger or other business combination or
with a third party approved by the Board of Directors of the Company since the
Board of Directors of the Company may, at its option, at any time prior to any
person becoming an Acquiring Person, redeem all but not less than all of the
then outstanding Rights at the Redemption Price.

        A Registration Statement on Form 8-A with respect to the Rights has 
been filed with the Securities and Exchange Commission. The Rights Agreement
specifying the terms of the Rights, the Certificate of Designation of the
Preferred Shares specifying the terms of the Preferred Shares (Exhibit A to the
Rights Agreement) and the form of Right Certificate (Exhibit B to the Rights
Agreement) are filed herewith as exhibits. The foregoing description of the
Rights does not purport to be complete and is qualified in its entirety by
reference to such exhibits, which are incorporated herein by reference.



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ITEM 7.  Exhibits.

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

  4.1        Rights Agreement dated as of December 9, 1998,
             between PRI Automation, Inc. and State Street
             Bank and Trust Company, as Rights Agent.
 
  4.2        Form of Certificate of Designation of Series A
             Participating Cumulative Preferred Stock of PRI
             Automation, Inc. (which is attached as Exhibit A
             to the Rights Agreement filed as Exhibit 4.1
             hereto).

  4.3        Form of Rights Certificate (which is attached
             as Exhibit B to the Rights Agreement filed as
             Exhibit 4.1 hereto).



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                            SIGNATURE


     Pursuant to the requirements of the Securities Exchange Act
of 1934, the registrant has duly caused this report to be signed
on its behalf by the undersigned hereunto duly authorized.

                            PRI AUTOMATION, INC.


Dated: December 9, 1998     By:  /s/ Mitchell G. Tyson
                                 -------------------------      
                                 Mitchell G. Tyson
                                 Chief Executive Officer
                                 and President


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                          EXHIBIT INDEX

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

  4.1        Rights Agreement dated as of December 9, 1998, 
             between PRI Automation, Inc. and State Street  
             Bank and Trust Company, as Rights Agent.        

  4.2        Form of Certificate of Designation of Series A   
             Participating Cumulative Preferred Stock of PRI 
             Automation, Inc. (which is attached as Exhibit  
             A to the Rights Agreement filed as Exhibit 4.1  
             hereto).                                         

  4.3        Form of Rights Certificate (which is attached
             as Exhibit B to the Rights Agreement filed as
             Exhibit 4.1 hereto).