In Russia, sexual transmission of HIV is increasing and street-based female sex workers (FSW) have a high HIV prevalence, but the role of male clients of FSW in HIV transmission and bridging to the general population has not been studied. Sixty-two male clients completed structured interviews during February-March of 2010 in St. Petersburg Russia. Descriptive analyses focused on condom use with different types of sex partners, substance use, and STI/HIV testing histories. The median lifetime and past 12 month numbers of FSW partners were 10 and 3, respectively. A majority of clients (74%) reported having non-FSW partners during the past 12 months, and nearly half (47%) reported having regular sex partners. Consistent condom use was reported in 61% of relationships with FSW partners and in 43% of relationships with non-FSW partners. A majority of clients (58%) was classified as active or potential bridgers based on having both FSW and non-FSW partners and reporting inconsistent condom use with their non-FSW partners. A majority (61%) also reported concurrent partnerships with FSW and non-FSW partners. Nearly half (48%) of last contacts with FSW partners involved consumption of alcohol by the client. Noninjection and injection drug use in the past 30 days were reported by 15% and 7% of clients, respectively. Twenty-nine percent reported history of a sexually transmitted infection (STI) and 74% reported a previous HIV test; active/potential bridgers were significantly less likely than unlikely bridgers to have ever been tested for HIV. These data signal the potential for HIV/STI transmission among male clients of street-based FSW in St. Petersburg Russia due to their variety of partner types, sub-optimal condom use, and concurrent partnerships. Larger studies are needed to confirm these findings, further explore the roles of alcohol and drug use, and identify effective strategies and interventions for HIV prevention.