The human immunodeficiency virus (HIV) epidemic in Eastern Europe and Central Asia continues to grow with most infections occurring in high-risk groups including people who inject drugs and their sexual partners. Labor migrants from this region who inject drugs while in Russia are at especially high HIV risk. Male Tajik migrant workers who inject drugs in Moscow (N = 420) were interviewed prior to a randomized trial of the Migrants’ Approached Self-Learning Intervention in HIV/AIDS (MASLIHAT) peer-education HIV-prevention intervention. Participants were interviewed about their sex and drug use behavior and tested for HIV and hepatitis C (HCV) prior to the intervention. Only 17% had ever been tested for HIV. Over half of the men reported injecting with a previously used syringe in the past month, and substantial proportions reported risky sexual behavior. Prevalence rates of HIV (6.8%) and HCV (2.9%) were elevated, although lower than expected when compared to estimates of prevalence among people who inject drugs at the national level in Tajikistan. Risk behavior in diaspora varied across the men’s regional area of origin in Tajikistan and occupation in Moscow, with HIV prevalence rates highest among those working at the bazaars. Evidence-based prevention approaches and messaging that specifically address the drug- and sex-related risk behavior of migrants with varying backgrounds are needed.