Exhibit 5.1 Opinion re legality of Dolgenos Newman & Cronin LLP 11 EXHIBIT 5.1 Dolgenos Newman & Cronin LLP ------------------------------------------------- 96 Spring Street, New York, N.Y. 10012 212-925 2800 Fax 212-925-0690 May 5, 1997 Avitar, Inc. 556 Washington Avenue, Suite 202 North Haven, Connecticut 06473 Tel.: (203) 234-7737 Gentlemen: We have acted as counsel to Avitar, Inc., a Delaware corporation (the "Company"), in connection with the Company's proposed offering of 1,400,000 shares of Common Stock, $0.01 par value as described in that certain Registration Statement (and the related Prospectus) on Form S-8 executed today by the Company and to be filed with the Securities and Exchange Commission on May 9, 1997 (as amended, the "Registration Statement" and "Prospectus"). In rendering this opinion we have examined copies of the Registration Statement; the Company's Certificate of Incorporation, as amended, and such other instruments, certificates and documents as we have deemed necessary or appropriate for the purpose of rendering this opinion. In such examinations, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals and the conformity to original documents submitted to us as copies. We have further assumed for the purpose of this opinion the due authorization and, as applicable, the due execution and delivery by, or on behalf of, each of the parties thereto of the above-referenced documents and all documents contemplated by the Registration Statement to be executed. Based on and subject to the foregoing, and limited in all respects to matters of New York law and the General Corporation Law of the State of Delaware, we are of the opinion that: 1. The Company is a corporation duly organized and validly existing under the laws of the State of Delaware. 12 Avitar, Inc. May 5, 1997 Page 2 2. The Company has authorized capitalization of thirty million shares, of which twenty-five million (25,000,000) shares are Common Stock, $0.01 par value, and five million (5,000,000) shares are Preferred Stock, $0.001 par value. 3. As of the date hereof, 12,077,195 shares of Common Stock have been duly and validly issued and are fully paid and non-assessable. 4. The shares of Common Stock included in the Registration Statement will, when issued in accordance with the terms and procedures set forth in the Registration Statement, constitute legally and validly issued, fully paid and non-assessable shares of Common Stock. We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement. Very truly yours, DOLGENOS NEWMAN & CRONIN LLP By: /s/EUGENE M. CRONIN 13