EXHIBIT 8.1




                                March 19, 2002


TIBCO Software Inc.
3165 Porter Drive
Palo Alto, California 94304

Ladies and Gentlemen:

   We have acted as counsel for TIBCO Software Inc., a Delaware corporation
("TIBCO"), in connection with the preparation and execution of the Agreement
and Plan of Merger dated as of January 4, 2002 (the "Agreement"), by and among
TIBCO, Talarian Corporation, a Delaware corporation ("Talarian"), and Panther
Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of
TIBCO ("Panther Acquisition"). Pursuant to the Agreement, one of the following
transactions will occur: (a) a forward triangular merger pursuant to which
Talarian will merge with and into Panther Acquisition, with Panther Acquisition
continuing as the surviving corporation and a wholly owned subsidiary of TIBCO,
(b) a reverse triangular merger pursuant to which Panther Acquisition will
merge with and into Talarian, with Talarian continuing as the surviving
corporation and becoming a wholly owned subsidiary of TIBCO, or (c) a reverse
triangular merger, pursuant to which Panther Acquisition will merge with and
into Talarian, with Talarian continuing as the surviving corporation, followed
by a second-step forward triangular merger pursuant to which Talarian as the
surviving corporation of the reverse triangular merger will merge with and into
another wholly owned subsidiary of TIBCO, with such subsidiary of TIBCO
continuing as the surviving corporation (each of the foregoing transactions is
hereafter referred to as the "Merger"). All section references, unless
otherwise indicated, are to the Internal Revenue Code of 1986, as amended (the
"Code").

   You have requested our opinion concerning the description of the material
United States federal income tax considerations of the Merger described in the
registration statement on Form S-4 filed with the Securities and Exchange
Commission, as amended at any time to and including the date hereof (the
"Registration Statement"). In delivering this opinion, we have reviewed and
relied upon (without any independent investigation) the facts, statements,
descriptions and representations set forth in the Agreement (including exhibits
thereto), the Registration Statement (including exhibits thereto), and such
other documents pertaining to the Merger as we have deemed necessary or
appropriate. We also have relied upon (without any independent investigation)
certificates of officers of TIBCO, Panther Acquisition and Talarian,
respectively (the "Officers' Certificates").

   In connection with rendering this opinion, we have assumed (without any
independent investigation) that:

   1.  Original documents (including signatures) are authentic, documents
submitted to us as copies conform to the original documents, and there has been
(or will be by the Effective Time of the Merger) due execution and delivery of
all documents where due execution and delivery are prerequisites to
effectiveness thereof.

   2.  Any representation or statement referred to above made "to the knowledge
of," "to the best of the knowledge" or otherwise similarly qualified is correct
without such qualification. As to all matters in which a person or entity
making a representation referred to above has represented that such person or
entity either is not a party to, does not have, or is not aware of, any plan,
intention, understanding or agreement, there is in fact no such plan,
intention, understanding or agreement.

   3.  All statements, descriptions and representations contained in any of the
documents referred to herein or otherwise made to us are true and correct in
all material respects and will continue to be true and correct in all
material respects as of the Effective Time and all other relevant times, and no
actions have been (or will be) taken which are inconsistent with such
representations.

   4.  The Merger will be reported by TIBCO, Talarian and Panther Acquisition
on their respective federal income tax returns in a manner consistent with the
opinion set forth below.



TIBCO Software, Inc.

March 19, 2002

Page 2


   5.  The Merger will be consummated in accordance with the Agreement (and
without any waiver, breach or amendment of any of the provisions thereof) and
will be effective under the applicable state laws.

   6.  An opinion of counsel, substantially identical in substance to this
opinion, has been delivered to Talarian by Fenwick & West LLP, and will not be
withdrawn prior to the Effective Date.

   Based on our examination of the foregoing items and subject to the
assumptions, exceptions, limitations and qualifications set forth herein and in
the Registration Statement, we are of the opinion that the discussion set forth
in the Registration Statement under the heading "Proposal No. 1--The
Merger--Material United States Federal Income Tax Considerations" constitutes,
in all material respects, a fair and accurate summary of the United States
federal income tax consequences of the Merger generally applicable to a
Talarian stockholder.

   This opinion represents and is based upon our best judgment regarding the
application of federal income tax laws arising under the Code, existing
judicial decisions, administrative regulations and published rulings and
procedures, all as in effect as of the date of this opinion. Our opinion is not
binding upon the Internal Revenue Service or the courts, and there is no
assurance that the Internal Revenue Service will not successfully assert a
contrary position. Furthermore, no assurance can be given that future
legislative, judicial or administrative changes, on either a prospective or
retroactive basis, would not adversely affect the accuracy of the conclusions
stated herein. Nevertheless, we undertake no responsibility to advise you of
any new developments in the application or interpretation of the federal income
tax laws.

   This opinion concerning certain of the United States federal tax
consequences of the Merger is limited to the specific United States federal tax
consequences presented above, and does not address any other federal, state,
local or foreign tax consequences that may result from the Merger or any other
transaction (including any transaction undertaken in connection with the
Merger).

   No opinion is expressed as to any transaction other than the Merger as
described in the Agreement or to any transaction whatsoever, including the
Merger, if all the transactions described in the Agreement are not consummated
in accordance with the terms of such Agreement and without waiver or breach of
any material provision thereof or if all of the representations, warranties,
statements and assumptions upon which we relied are not true and accurate at
all relevant times. In the event any one of the statements, representations,
warranties or assumptions upon which we have relied to issue this opinion is
incorrect, our opinion might be adversely affected and may not be relied upon.

   We consent to the use of this opinion as an exhibit to the Registration
Statement, to references to this opinion in the Registration Statement and to
the use of our name in the Registration Statement. In giving this consent, we
do not admit that we are within the category of persons whose consent is
required under Section 7 of the Securities Act of 1933, as amended (the
"Securities Act") or the rules or regulations promulgated thereunder or that we
are experts with respect to any portions of the S-4 Registration Statement
within the meaning of the term "experts" as used in the Securities Act, or the
rules or regulations promulgated thereunder. The filing of this opinion as an
exhibit to the S-4 Registration Statement and the references to the opinion and
our firm therein are not intended to create liability under applicable state
law to any person other than TIBCO, our client.

                                          Very truly yours,

                                          VENTURE LAW GROUP
                                          A Professional Corporation


                                          /s/  VENTURE LAW GROUP