Exhibit 8.1

              [Skadden, Arps, Slate, Meagher & Flom LLP letterhead]




                                                  December 18, 2003




EMC Corporation
176 South Street
Hopkinton, MA  01748

Ladies and Gentlemen:

            We have acted as tax counsel to EMC Corporation ("EMC"), a
Massachusetts corporation, in connection with (i) the Initial Merger, as
described in the Agreement and Plan of Merger, dated as of October 13, 2003 (the
"Merger Agreement"), by and among EMC, Elite Merger Corporation, a Delaware
corporation and a wholly-owned subsidiary of EMC ("Merger Sub") and Documentum,
Inc., a Delaware corporation ("Documentum"), and (ii) the preparation and filing
of the registration statement on Form S-4 (the "Registration Statement") with
the Securities and Exchange Commission (the "Commission") under the Securities
Act of 1933, as amended, on October 28, 2003 and Amendment No. 1 thereto filed
with the Commission on November 18, 2003 (such Registration Statement, as so
amended, herein called the "Registration Statement"), which includes a proxy
statement/prospectus (the "Proxy Statement/Prospectus"). We understand that EMC
will merge Documentum with and into EMC pursuant to an integrated plan as soon
as practicable following the Closing, but in no event later than December 31,
2003 (the "Subsequent Merger," and collectively with the Initial Merger, the
"Merger"). At your request and pursuant to Section 7.1(g) of the Merger
Agreement, we are rendering our opinion concerning certain United States federal
income tax consequences of the Merger. Unless otherwise indicated, each
capitalized term used herein has the meaning ascribed to it in the Merger
Agreement.


            In connection with this opinion, we have examined the Merger
Agreement, the Proxy Statement/Prospectus and such other documents as we have
deemed necessary or appropriate in order to enable us to render the opinion
below. We have relied, with the consent of EMC and the consent of Documentum,
upon statements, representations and covenants made by EMC, Documentum and
Merger Sub, including representations and covenants made to us by EMC,
Documentum and Merger Sub in their respective representation letters dated as of
the date hereof and delivered to us for purposes of this opinion, and have
assumed that such statements and representations are true without regard to any
qualifications as to knowledge and belief. For purposes of this opinion, we have
assumed (i) the validity and accuracy of the documents and corporate


EMC Corporation
December 18, 2003
Page 2


records that we have examined and the facts and representations concerning the
Merger that have come to our attention during our engagement, (ii) the
genuineness of all signatures, the legal capacity of all natural persons, the
authenticity of all documents submitted to us as originals, the conformity to
original documents of all documents submitted to us as certified or photostatic
copies and the authenticity of the originals of such documents, (iii) that the
Merger will be consummated in accordance with the terms of the Merger Agreement
and as described in the Proxy Statement/Prospectus and that none of the terms
and conditions contained therein will have been waived or modified in any
respect prior to the Effective Time, and (iv) that the Initial Merger will
qualify as a statutory merger under the applicable laws of the State of Delaware
and the Subsequent Merger will qualify as a statutory merger under the
applicable laws of the State of Delaware and the applicable laws of the
Commonwealth of Massachusetts.


            In rendering our opinion, we have considered the applicable
provisions of the Code, Treasury Department regulations promulgated thereunder,
pertinent judicial authorities, interpretive rulings of the Internal Revenue
Service (the "IRS") and such other authorities as we have considered relevant.
It should be noted that statutes, regulations, judicial decisions and
administrative interpretations are subject to change at any time (possibly with
retroactive effect). A change in the authorities or the truth, accuracy or
completeness of any of the facts, information, documents, corporate records,
covenants, statements, representations or assumptions on which our opinion is
based could affect our conclusions. Further, there can be no assurances that the
opinion expressed herein will be accepted by the IRS or, if challenged, by a
court.

            Subject to the assumptions set forth above, in our opinion the
Initial Merger, or in the event the Subsequent Merger occurs pursuant to an
integrated plan, the Initial Merger and the Subsequent Merger taken together
will qualify as a reorganization within the meaning of Section 368(a) of the
Code. The opinion set forth above does not address all of the United States
federal income tax consequences of the Merger. Except as expressly set forth
above, we express no other opinion, including, without limitation, any opinion
as to the United States federal, state, local, foreign or other tax
consequences. This opinion is expressed as of the date hereof, and we are under
no obligation to supplement or revise our opinion to reflect any changes
(including changes that have retroactive effect) (i) in applicable law or (ii)
in any fact, information, document, corporate record, covenant, statement,
representation or assumption stated herein that becomes untrue, incorrect or
incomplete.

            This opinion has been prepared for you in connection with the
Merger, as described in the Merger Agreement and the Proxy Statement/Prospectus.
It may not be relied upon by anyone else without our prior written consent.

                                    Very truly yours,

                                    /s/ Skadden, Arps, Slate, Meagher & Flom LLP