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                                                                     EXHIBIT 5.1

                         [PEPE & HAZARD LLP LETTERHEAD]


                                               May 28, 1999



Bio-Plexus, Inc.
129 Reservoir Road
Vernon, CT 06066

         RE:   Registration Statement on Form S-3 of Bio-Plexus, Inc.
               (the"Company")

Ladies and Gentlemen:

         We have acted as counsel to Bio-Plexus, Inc., a Connecticut corporation
(the "Company"), with respect to the offering by certain selling shareholders of
up to 3,500,000 shares (the "Shares") of the Common Stock of the Company,
without par value per share (the "Common Stock") under the Registration
Statement, filed by the Company under the Securities Act of 1933, as amended. As
such counsel, we have examined such corporate records, certificates and other
documents and have made such other factual and legal investigations as we have
deemed relevant and necessary as the basis for the opinions hereinafter
expressed. In such examinations, we have assumed the genuineness of all
signatures and the authenticity of all documents submitted to us as originals
and the conformity to original documents of all documents submitted to us as
conformed or photostatic copies. Unless otherwise defined herein, capitalized
terms shall have the meanings assigned to them in the Registration Statement.
Based on the foregoing, we are of the opinion that:

         1. The shares of Common Stock initially issuable upon the exercise of
the warrants covered by the Registration Statement have been duly authorized and
reserved for issuance, and upon exercise of such warrants and the payment of the
exercise price in accordance with the terms of the warrants, such shares of
Common Stock will be validly issued, fully paid, and non-assessable by the
Company.

         2. The shares of Common Stock initially issuable upon the conversion of
the each of the Debentures by the Company Stockholders have been duly authorized
and reserved for issuance, and upon issuance, each will be validly issued, fully
paid, and non-assessable by the Company.


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Bio-Plexus, Inc.
May 28, 1999
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         3. The other shares of Common Stock covered by the Registration
Statement have been duly authorized, are fully paid, and non-assessable by the
Company.

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

                                              Very truly yours,

                                              PEPE & HAZARD LLP



                                              By:   /s/ Walter W. Simmers
                                                    ----------------------------
                                                        Walter W. Simmers
                                                        A Partner