EXHIBIT 5.1 OPINION RE: LEGALITY -10- ---------------- LILLICK --------&------- CHARLES ---------------- LLP ATTORNEYS AT LAW Two Embarcadero Center Phone: 415-984-8200 San Francisco, CA 94111-3996 Fascimile: 415-984-8300 December 21, 1999 Writer's Email Address Writer's Direct Dail Number rfaye@lillick.com 415-984-8365 North Bay Bancorp 1500 Soscol Avenue Napa, California 94559 Ladies and Gentlemen: With reference to the Registration Statement on Form S-8 filed by North Bay Bancorp ("North Bay") with the Securities and Exchange Commission in connection with the registration under the Securities Act of 1933, as amended, of 337,211 shares of North Bay Common Stock, no par value, (the "Shares") to be issued in connection with the grant and exercise of options under the North Bay Bancorp 1999 Stock Option Plan (the "Stock Option Plan"): We are of the opinion that the Shares have been duly authorized and, when issued in accordance with the Stock Option Plan, will be validly issued, fully paid and nonassessable. We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement, and any amendments thereto, and the use of our name under the caption "Legal Matters" in the Registration Statement, and any amendments thereto, and in the Prospectus included therein. Very truly yours, /s/ Lillick & Charles LLP LILLICK & CHARLES LLP