The purpose of this study was to establish the prevalence of high-risk sexual behaviors and drug-using behaviors in a large community sample of male and female injection drug users (IDUs) in St. Petersburg, Russia. This investigation used a data collection plan that systematically recruited a drug user sample from venues where IDUs were known to congregate and could be accessed. Surveys were completed by 239 IDUs (males = 139, females = 100), aged 13-25. Participants averaged 44 injections (range = 0-240) in the past 30 days, with heroin (70%) and heroin plus other drugs (20%) the most frequently used. Participants' mean age of first drug injecting was 17.6 years, 41% of participants regularly shared needles, most had multiple sexual partners (mean = 9.3 partners in the past 3 months), and 70% reported engaging in vaginal intercourse without condoms. Stepwise logistic regression showed that high-risk sexual behavior was predicted by being female, young, using heroin several times a month, and less negative attitudes toward using condoms. Effective HIV prevention efforts for IDUs in Russia must be tailored to their age, gender, drug use, and condom attitudes. These programs will also have to address the dual risk factors, unique to IDUs, of risky sexual behaviors and needle sharing. Without a rapid intervention response, Russia's HIV/AIDS crisis will soon turn catastrophic.