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                                                                      Exhibit 5
                                                                      ---------


                                September 9, 1996


Aspen Technology, Inc.
Ten Canal Park
Cambridge, Massachusetts  02141

Ladies and Gentlemen:

         We have acted as counsel for Aspen Technology, Inc., a Massachusetts
corporation (the "Company"), in connection with the Company's Registration
Statement on Form S-8 proposed to be filed with the Securities and Exchange
Commission on or about September 9, 1996 (the "Registration Statement").

         The Registration Statement covers the registration of 1,654,685 shares
of common stock, par value $.10 per share, of the Company (the "Shares"), which
are to be issued by the Company upon exercise of stock options granted or to be
granted pursuant to the Company's 1995 Stock Option Plan, 1995 Directors Stock
Option Plan, and 1995 Employees' Stock Purchase Plan (collectively, the
"Plans").

         We have reviewed the corporate proceedings of the Company with respect
to the authorization of the Plans and the issuance of the Shares thereunder. We
have also examined and relied upon originals or copies of such agreements,
instruments, corporate records, certificates, and other documents as we have
deemed necessary or appropriate as a basis for the opinions hereinafter
expressed. In our examination, we have assumed the genuineness of all
signatures, the conformity to the originals of all documents reviewed by us as
copies, the authenticity and completeness of all original documents reviewed by
us in original or copy form, and the legal competence of each individual
executing any document.

         We further assume that all Shares issued upon exercise of options
granted or to be granted pursuant to the Plans will be issued in accordance with
the terms of such options and the Plans.

         Subject to the limitations set forth below, we have made such
examination of law as we have deemed necessary for the purposes of this opinion.
This opinion is limited solely to the Massachusetts Business Corporation Law.

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Aspen Technology, Inc.
September 9, 1996
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         Based upon and subject to the foregoing, we are of the opinion that the
Shares, when issued and delivered upon the exercise of options duly granted
pursuant to the Plans and against the payment of the purchase price or exercise
price therefor as provided in the Plans and the instrument evidencing the
relevant grant, will be validly issued, fully paid, and non-assessable.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.

                                            Very truly yours,

                                            /s/ Bingham, Dana & Gould LLP


                                            BINGHAM, DANA & GOULD LLP