AMENDMENT #5 TO CONSULTING AGREEMENT


 EXHIBIT 10.6

 AMENDMENT #5 TO

 CONSULTING AGREEMENT

      This Amendment #5 To
   Consulting Agreement, dated as of February 10, 2000, hereby amends the terms
   of that certain Consulting Agreement dated November 17, 1995, as amended,
   (hereinafter "Consulting Agreement") by and between Parametric
   Technology Corporation, a Massachusetts corporation, having its principal
   business address at 128 Technology Drive, Waltham, Massachusetts 02453
   (hereinafter "PTC") and Michael E. Porter, an individual currently
   residing at 44 Green Hill Road, Brookline, Massachusetts 02146 (hereinafter
   "Consultant").

 Article 3 Services To Be Performed By
   Consultant, is hereby amended by adding the following Section
   3.5:

  3.5   Consultant is engaged pursuant
   to this Amendment #5 to Consulting Agreement, to participate in five (5) top
   management seminars, including Chief Information Officer (CIO) seminars,
   consistent with the purposes and scope which Consultant was previously
   engaged to provide under Sections 3.2, 3.3 and 3.4 of the Consulting
   Agreement.

 

 Article 4 Compensation And Expenses, is hereby
   amended by adding the following Section 4.6:

  4.6   Option grant for services to be
   performed under Section 3.5. In connection with those services to be
   performed pursuant to this Amendment #5 to Consulting Agreement (as
   described in Section 3.5 above), Consultant shall receive an option to
   purchase 50,000 shares of PTC's common stock, $.01 par value per share,
   under the terms of the Stock Option Agreement dated February 10, 2000
   between PTC and the Consultant attached hereto.

 

      IN WITNESS WHEREOF, the
   parties have executed this Amendment #5 to Consulting Agreement as of the
   date and year first above written.

 	Consultant	 	Parametric Technology Corporation
	 	 	 
	 	 	 
	/s/ Michael E. Porter	 	/s/ Steven C. Walske 
	 
 	 	 
 
	Michael E. Porter	 	Steven C. Walske
	 	 	 Chairman and Chief Executive Officer 



 	 No. 030457

   	 50,000 Shares

   


 PARAMETRIC TECHNOLOGY CORPORATION 1997
 

 Incentive Stock Option Plan

 Nonstatutory Stock Option Certificate

 February 10, 2000

      Parametric Technology
   Corporation (the "Company"), a Massachusetts corporation, hereby
   grants to the person named below an option to purchase shares of Common
   Stock, $0.01 par value, of the Company (the "Option") under and
   subject to the Company's 1997 Incentive Stock Option Plan (the
   "Plan") exercisable on the following terms and conditions set
   forth below and those attached hereto and in the Plan:

 	Name of Optionholder: 	Michael E. Porter
	 	 
	Social Security Number	###-##-####
	 	 
	Number of Shares:	50,000
	 	 
	Option Price:	$22.9375
	 	 
	Date of Grant: 	February 10, 2000 
	 	 
	Expiration:	February 10, 2005
	 	 
	Exercisability Schedule:	 


           on or
   after      February 10, 2000, as to 50% of the
   shares,
 

           on or
   after      April 2, 2000, as to 50% of the
   shares,

 



 
 
  provided that Optionholder's consulting agreement with
   the Company is not terminated earlier, in which event the Option, (i) to the
   extent exercisable at the date of such termination, may not be exercised as
   to any shares after the expiration of seven (7) months from the date of such
   termination, and (ii) to the extent not exercisable at the date of such
   termination, shall be canceled as to any such shares effective on the date
   of such termination.

 

           This
   Option shall not be treated as an Incentive Stock Option under section 422
   of the Internal Revenue Code of 1986, as amended.

           By
   acceptance of this Option, the Optionholder agrees to the terms and
   conditions set forth above and those attached hereto and in the
   Plan.

 	OPTIONHOLDER	 	PARAMETRIC TECHNOLOGY CORPORATION
	 	 	 	 	 
	By: 	 /s/ Michael E. Porter 
 	 	By: 	 /s/ Edwin J. Gillis 
 
	 	Optionholder	 	 	Executive Vice President - CFO


  

 PARAMETRIC TECHNOLOGY CORPORATION 1997 INCENTIVE STOCK
   OPTION PLAN

 Nonstatutory Stock Option Terms And
   Conditions

           1.
         Plan Incorporated by Reference. This
   Option is issued pursuant to the terms of the Plan and may be amended as
   provided in the Plan. Capitalized terms used and not otherwise defined in
   this certificate have the meanings given to them in the Plan. This
   certificate does not set forth all of the terms and conditions of the Plan,
   which are incorporated herein by reference. The Committee administers the
   Plan and its determinations regarding the operation of the Plan are final
   and binding. Copies of the Plan may be obtained upon written request without
   charge from the Corporate Counsel of the Company.

           2.
         Option Price. The price to be paid for
   each share of Common Stock issued upon exercise of the whole or any part of
   this Option is the Option Price set forth on the face of this
   certificate.

           3.
         Exercisability Schedule. This Option
   may be exercised at any time and from time to time for the number of shares
   and in accordance with the exercisability schedule set forth on the face of
   this certificate, but only for the purchase of whole shares. This Option may
   not be exercised as to any shares after the Expiration Date.

           4.
         Method of Exercise. To exercise this
   Option, the Optionholder shall deliver written notice of exercise to the
   Company specifying the number of shares with respect to which the Option is
   being exercised accompanied by payment of the Option Price for such shares
   in cash, by certified check or in such other form, including shares of
   Common Stock of the Company valued at their Fair Market Value on the date of
   delivery or a payment commitment of a financial or brokerage institution, as
   the Committee may approve. Promptly following such notice, the Company will
   deliver to the Optionholder a certificate representing the number of shares
   with respect to which the Option is being exercised.

           5.
         No Right To Employment. No person
   shall have any claim or right to be granted an Option. Each employee of the
   Company or any of its Affiliates is an employee-at-will (that is to say that
   either the Participant or the Company or any Affiliate may terminate the
   employment relationship at any time for any reason or no reason at all)
   unless, and only to the extent, provided in a written employment agreement
   for a specified term executed by the chief executive officer of the Company
   or his duly authorized designee or the authorized signatory of any
   Affiliate. Neither the adoption, maintenance, nor operation of the Plan nor
   any Option hereunder shall confer upon any employee of the Company or of any
   Affiliate any right with respect to the continuance of his/her employment by
   the Company or any such Affiliate nor shall they interfere with the right of
   the Company (or Affiliate) to terminate any employee at any time or
   otherwise change the terms of employment, including, without limitation, the
   right to promote, demote or otherwise re-assign any employee from one
   position to another within the Company or any Affiliate.

           6.
         Effect of Grant. Participant shall not
   earn any Options granted hereunder until such time as all the conditions put
   forth herein and in the Plan which are required to be met in order to
   exercise the Option have been fully satisfied.

           7.
        Recapitalization, Mergers, Etc. As
   provided in the Plan, in the event of corporate transactions affecting the
   Company's outstanding Common Stock, the number and kind of shares subject to
   this Option and the exercise price hereunder shall be equitably adjusted. If
   such transaction involves a consolidation or merger of the Company with
   another entity, the sale or exchange of all or substantially all of the
   assets of the Company or a reorganization or liquidation of the Company,
   then in lieu of the foregoing, the Committee may upon written notice to the
   Optionholder provide that this Option shall terminate on a date not less
   than 20 days after the date of such notice unless theretofore exercised. In
   connection with such notice, the Committee may in its discretion accelerate
   or waive any deferred exercise period.

           8.
         Option Not Transferable. This Option
   is not transferable by the Optionholder otherwise than by will or the laws
   of descent and distribution, and is exercisable, during the Optionholder's
   lifetime, only by the Optionholder. The naming of a Designated Beneficiary
   does not constitute a transfer.

           9.
         Termination of Employment or
   Engagement. If the Optionholder's status as an employee or consultant of
   (a) the Company, (b) an Affiliate, or (c) a corporation (or parent or
   subsidiary corporation of such corporation) issuing or
 assuming a stock option in a transaction to which section 424(a) of the Code
   applies, is terminated for any reason (voluntary or involuntary) and the
   period of exercisability for a particular Option following such termination
   has not been specified by the Board, each such Option then held by that
   Participant shall expire to the extent not previously exercised ten (10)
   calendar days after such Participant's employment or engagement is
   terminated, except that-

      (a)      If
   the Participant is on military, sick leave or other bona fide
   leave of absence (such as temporary employment by the federal government),
   his or her employment or engagement with the Company will be treated as
   continuing intact if the period of such leave does not exceed ninety (90)
   days, or, if longer, so long as the Participant's right to reemployment or
   the survival of his or her service arrangement with the Company is
   guaranteed either by statute or by contract; otherwise, the Participant's
   employment or engagement will be deemed to have terminated on the 91st day
   of such leave.

      (b)      If
   the Participant's employment is terminated by reason of his or her
   retirement from the Company at normal retirement age, each Option then held
   by the Participant, to the extent exercisable at retirement, may be
   exercised by the Participant at any time within three (3) months after such
   retirement unless terminated earlier by its terms.

      (c)      If
   the Participant's employment or engagement is terminated by reason of his or
   her death, each Option then held by the Participant, to the extent
   exercisable at the date of death, may be exercised at any time within one
   year after that date (unless terminated earlier by its terms) by the
   person(s) to whom the Participant's option rights pass by will or by the
   applicable laws of descent and distribution.

      (d)      If
   the Participant's employment or engagement is terminated by reason of his or
   her becoming permanently and totally disabled, each Option then held by the
   Participant, to the extent exercisable upon the occurrence of permanent and
   total disability, may be exercised by the Participant at any time within one
   (1) year after such occurrence unless terminated earlier by its terms. For
   purposes hereof, an individual shall be deemed to be "permanently and
   totally disabled" if he or she is unable to engage in any substantial
   gainful activity by reason of any medically determinable physical or mental
   impairment which can be expected to result in death or which has lasted or
   can be expected to last for a continuous period of not less than twelve (12)
   months. Any determination of permanent and total disability shall be made in
   good faith by the Company on the basis of a report signed by a qualified
   physician.

           10.
         Compliance with Securities Laws. It
   shall be a condition to the Optionholder's right to purchase shares of
   Common Stock hereunder that the Company may, in its discretion, require (a)
   that the shares of Common Stock reserved for issuance upon the exercise of
   this Option shall have been duly listed, upon official notice of issuance,
   upon any national securities exchange or automated quotation system on which
   the Company's Common Stock may then be listed or quoted, (b) that either (i)
   a registration statement under the Securities Act of 1933 with respect to
   the shares shall be in effect, or (ii) in the opinion of counsel for the
   Company, the proposed purchase shall be exempt from registration under that
   Act and the Optionholder shall have made such undertakings and agreements
   with the Company as the Company may reasonably require, and (c) that such
   other steps, if any, as counsel for the Company shall consider necessary to
   comply with any law applicable to the issue of such shares by the Company
   shall have been taken by the Company or the Optionholder, or both. The
   certificates representing the shares purchased under this Option may contain
   such legends as counsel for the Company shall consider necessary to comply
   with any applicable law.

           11.
         Payment of Taxes. The Optionholder
   shall pay to the Company, or make provision satisfactory to the Company for
   payment of, any taxes required by law to be withheld with respect to the
   exercise of this Option. The Committee may, in its discretion, require any
   other Federal or state taxes imposed on the sale of the shares to be paid by
   the Optionholder. In the Committee's discretion, such tax obligations may be
   paid in whole or in part in shares of Common Stock, including shares
   retained from the exercise of this Option, valued at their Fair Market Value
   on the date of delivery. The Company and its Affiliates may, to the extent
   permitted by law, deduct any such tax obligations from any payment of any
   kind otherwise due to the Optionholder.

           Adopted
   November 14, 1996