The study examined the efficacy of a brief theory-based counseling intervention to reduce sexual HIV risk behaviors among STI clinic patients in St. Petersburg, Russia. Men and women (n = 307) were recruited to receive either: (1) a 60-minute motivational/skills-building counseling session dealing with sexual HIV risk reduction, or (2) written HIV prevention information material. Participants completed baseline, three- and six-month assessments in the period between July 2009 and May 2011. Compared to the control group, the face-to-face counseling intervention showed significant increases in the percentage of condom use and consistent condom use, and significant decreases in the number of unprotected sexual acts and frequency of drug use before sex. Intervention effects dissipated by 6 months. The brief counseling intervention may effectively reduce HIV sexual risk behaviors and enhance protective behaviors among STI clinic patients in Russia. Short-term positive effects were achieved with a single one hour counseling session.