EXHIBIT 5.1

                                HALE AND DORR LLP
                               Counsellors At Law

                60 State Street, Boston, Massachusetts 02109
                     TEL 617-526-6000 * FAX 617-526-5000

                                 August 10, 2000

Innoveda, Inc.
293 Boston Post Road West
Marlboro, Massachusetts 01752

       Re:  REGISTRATION STATEMENT ON FORM S-4

Ladies and Gentlemen:

         This opinion is furnished to you in connection with a Registration
Statement on Form S-4, as may be amended from time to time (the "Registration
Statement"), filed with the Securities and Exchange Commission (the
"Commission") under the Securities Act of 1933, as amended (the "Securities
Act"), for the registration of 6,473,136 shares of Common Stock, $0.01 par value
per share (the "Shares"), of Innoveda, Inc., a Delaware corporation (the
"Company"), issuable pursuant to the Agreement and Plan of Merger and
Reorganization, dated as of June 2, 2000 (the "Merger Agreement"), by and among
the Company, Innovative Software, Inc., a Delaware corporation and a
wholly owned subsidiary of the Company, and PADS Software, Inc., a Delaware
corporation.

         We are acting as counsel for the Company in connection with the
issuance by the Company of the Shares. We have examined signed copies of the
Registration Statement as filed with the Commission. We have also examined and
relied upon the Merger Agreement, minutes of meetings of the stockholders and
the Board of Directors of the Company as provided to us by the Company, record
books of the Company as provided to us by the Company, the Certificate of
Incorporation and By-Laws of the Company, each as restated and/or amended to
date, and such other documents as we have deemed necessary for purposes of
rendering the opinions hereinafter set forth.

         In our examination of the foregoing documents, we have assumed the
genuineness of all signatures, the authenticity of all documents submitted to us
as originals, the conformity to original documents of all documents submitted to
us as copies, the authenticity of the originals of such latter documents and the
legal competence of all signatories to such documents.

         We assume that the appropriate action will be taken, prior to the offer
and sale of the Shares in accordance with the Merger Agreement, to register and
qualify the Shares for sale under all applicable state securities or "blue sky"
laws.

         We express no opinion herein as to the laws of any state or
jurisdiction other than the state laws of the Commonwealth of Massachusetts, the
General Corporation Law


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Innoveda, Inc.
August 10, 2000
Page 2

statute of the State of Delaware and the federal laws of the United States of
America. To the extent that any other laws govern the matters as to which we
are opining herein, we have assumed that such laws are identical to the state
laws of the Commonwealth of Massachusetts, and we are expressing no opinion
herein as to whether such assumption is reasonable or correct.

         Based upon and subject to the foregoing, we are of the opinion that the
Shares have been duly authorized for issuance and, when the Shares are issued
and paid for in accordance with the terms and conditions of the Merger
Agreement, the Shares will be validly issued, fully paid and nonassessable.

          It is understood that this opinion is to be used only in connection
with the offer and sale of the Shares while the Registration Statement is in
effect.

         Please note that we are opining only as to the matters expressly set
forth herein, and no opinion should be inferred as to any other matters. This
opinion is based upon currently existing statutes, rules, regulations and
judicial decisions, and we disclaim any obligation to advise you of any change
in any of these sources of law or subsequent legal or factual developments which
might affect any matters or opinions set forth herein.

         We hereby consent to the filing of this opinion with the Commission as
an exhibit to the Registration Statement in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act and to the use of our
name therein and in the related Prospectus under the caption "Legal Matters." In
giving such consent, we do not hereby admit that we are in the category of
persons whose consent is required under Section 7 of the Securities Act or the
rules and regulations of the Commission.

                                   Very truly yours,

                                   /s/ HALE AND DORR LLP

                                   HALE AND DORR LLP