The purpose of this analysis was to estimate human immunodeficiency virus (HIV) prevalence and testing patterns among injection drug users (IDUs) in St. Petersburg, Russia. HIV prevalence among 387 IDUs in the sample was 50%. Correlates of HIV-positive serostatus included unemployment, recent unsafe injections, and history/current sexually transmitted infection. Seventy-six percent had been HIV tested, but only 22% of those who did not report HIV-positive serostatus had been tested in the past 12 months and received their test result. Correlates of this measure included recent doctor visit and having been in prison or jail among men. Among the 193 HIV-infected participants, 36% were aware of their HIV-positive serostatus. HIV prevalence is high and continuing to increase in this population. Adequate coverage of HIV testing has not been achieved, resulting in poor knowledge of positive serostatus. Efforts are needed to better understand motivating and deterring factors for HIV testing in this setting.