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                                                                    EXHIBIT 99.3

November 3, 2000

Board of Directors, PanVera Corporation
545 Science Drive
Madison, WI 53711

Gentlemen:

     PanVera Corporation, a Wisconsin corporation (the "Company"), proposes to
enter into an Agreement and Plan of Merger and Reorganization (the "Agreement")
with Aurora Biosciences Corporation, a Delaware corporation, ("Buyer") and
Angora Acquisition Corporation, a Wisconsin corporation and a wholly owned
subsidiary of Buyer ("Merger Sub"). All capitalized terms used herein and not
otherwise defined shall have the same meaning ascribed to such terms in the
Agreement. Pursuant to the Agreement, at the Effective Time, Merger Sub will
merge with and into the Company with the Company being the surviving corporation
(the "Merger"). Pursuant to the Merger, each share of Company Common Stock
outstanding immediately prior to the Effective Time (other than Dissenting
Shares, if any) will be converted into the right to receive that fraction of a
share of Parent Common Stock equal to the Applicable Fraction (as hereinafter
defined). Pursuant to the Agreement, 7.5% of the shares of Parent Common Stock
issuable pursuant to the Merger will be held in escrow (the "Escrow Shares") to
satisfy certain specified indemnification obligations of the stockholders of the
Company.

     The "Applicable Fraction" means the fraction (A) having a numerator equal
to 1,900,000 and (B) having a denominator equal to the Fully Diluted Company
Share Amount. Assuming that the Fully Diluted Company Share Amount is 1,416,051
shares of Company Common Stock (based on the shares of the Company Common Stock
currently outstanding and assuming that all outstanding options are exercised in
conjunction with the Merger), the Applicable Fraction would be 1.342 shares of
Parent Common Stock (the "Exchange Ratio").

     You have requested our opinion as to the fairness, from a financial point
of view, of the Exchange Ratio to the holders of Company Common Stock (other
than Buyer and its affiliates).

     Robert W. Baird & Co. Incorporated ("Baird"), as part of its investment
banking business, is engaged in the evaluation of businesses and their
securities in connection with mergers and acquisitions, negotiated
underwritings, competitive biddings, secondary distributions of listed and
unlisted securities, private placements, and valuations for estate, corporate
and other purposes.

     In conducting our investigation and analysis and in arriving at our opinion
herein, we have reviewed such information and taken into account such financial
and economic factors as we have deemed relevant under the circumstances. In that
connection, we have, among other things: (i) reviewed certain internal
information, primarily financial in nature, including projections, concerning
the business and operations of the Company furnished to us for purposes of our
analysis, as well as publicly available information; (ii) reviewed certain
publicly available information, primarily financial in nature, concerning the
business and operations of the Buyer including but not limited to Buyer's recent
filings with the Securities and Exchange Commission and equity analyst research
reports prepared by various investment banking firms; (iii) reviewed the draft
Agreement in the form presented to the Company's Board of Directors; (iv)
compared the historical market prices and trading activity of the Buyer's common
stock with those of certain other publicly traded companies we deemed relevant;
(v) compared the financial position and operating results of the Company and
Buyer with those of other publicly traded companies we deemed relevant; (vi)
compared the proposed financial terms of the Merger with the financial terms of
certain other business combinations we deemed relevant; and (vii) reviewed
certain potential pro forma financial effects of the Merger. We have held
discussions with certain members of the Company's and Buyer's respective senior
management concerning the Company's and Buyer's historical and current financial
condition and operating results, as well as the future prospects of the Company
and Buyer, respectively. We have not been requested to, and did not, solicit
third party indications of interest in acquiring all or


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any part of the Company. We have also considered such other information,
financial studies, analysis and investigations and financial, economic and
market criteria which we deemed relevant for the preparation of this opinion.

     In arriving at our opinion, we have assumed and relied upon the accuracy
and completeness of all of the financial and other information that was publicly
available or provided us by or on behalf of the Company and the Buyer, and have
not been engaged to and we did not independently verify any such information. We
have assumed, with your consent, that: (i) all material assets and liabilities
(contingent or otherwise, known or unknown) of the Company and the Buyer are as
set forth in their respective financial statements; (ii) the Merger will be
accounted for as a pooling-of-interests under generally accepted accounting
principles; (iii) the Merger will qualify as a tax free reorganization under the
provisions of Section 368(a) of the Internal Revenue Code of 1986, as amended;
(iv) the Merger will be consummated in accordance with the terms of the
Agreement, without any amendment thereto and without waiver by the Company or
Buyer of any of the conditions to their respective obligations thereunder; and
(v) there will be no reduction in the Exchange Ratio resulting from any
indemnification claims secured by the Escrow Shares. We have also assumed that
the financial forecasts examined by us were reasonably prepared on bases
reflecting the best available estimates and good faith judgments of the
Company's senior management as to future performance of the Company and that the
Company will perform in accordance with such financial forecasts within the time
frames indicated. At the direction of the Company, we have not considered any
potential expense increases, cost savings or operating synergies that might
result from the Merger and have excluded transaction expenses relating to the
Merger from our analyses. In conducting our review, we have not undertaken nor
obtained an independent evaluation or appraisal of any of the assets or
liabilities (contingent or otherwise) of the Company or Buyer, nor have we made
a physical inspection of the properties or facilities of the Company or Buyer.
Our opinion necessarily is based upon economic, monetary and market conditions
as they exist and can be evaluated on the date hereof, and does not predict or
take into account any changes which may occur, or information which may become
available, after the date hereof. Furthermore, we express no opinion as to the
price or trading range at which the Buyer's securities will trade following the
date hereof.

     Our opinion has been prepared at the request and for the information of the
Board of Directors of the Company, and shall not be used for any other purpose
or disclosed to any other party without the prior written consent of Baird;
provided, however, that this letter may be reproduced in full in the Company
Proxy Statement to be provided to the Company's shareholders in connection with
the Merger. This opinion does not address the relative merits of the Merger and
any other potential transactions or business strategies considered by the
Company's Board of Directors, and does not constitute a recommendation to any
shareholder of the Company as to how any such shareholder should vote with
respect to the Merger. Baird will receive a fee for rendering this opinion and
the Company has agreed to indemnify us for certain liabilities that may arise
out of our engagement.

     In the ordinary course of our business, we may from time to time trade the
securities of the Buyer for our own account or the accounts of our customers
and, accordingly, may at any time hold long or short positions in such
securities.

     Based upon and subject to the foregoing, we are of the opinion that, as of
the date hereof, the Exchange Ratio is fair, from a financial point of view, to
the holders of Company Common Stock (other than Buyer and its affiliates).

                                          Very truly yours,

                                          ROBERT W. BAIRD & CO. INCORPORATED