Background: The Russian human immunodeficiency virus (HIV) epidemic among people who inject drugs (PWID) originated in Kaliningrad, but research into risk behaviours among PWID has been lacking. The potential for heterosexual spread has not been analysed. Methods: A sample of PWID was accrued using two methods. A questionnaire was administered to assess HIV-related risk behaviours for parenteral and sexual transmission, sociodemographic factors, HIV knowledge and attitudes about sexual risks. Data were analysed focusing on the role of imprisonment, factors associated with awareness of being HIV infected and condom use. Results: More than a quarter of the sample reported having been diagnosed with HIV infection, with higher prevalence among women and those with a history of incarceration. More than half reported having been diagnosed with hepatitis C virus infection. Those reporting being HIV positive were less likely to distribute used syringes to other PWID and more likely to have used a condom the last time they had sex. A history of incarceration was associated with higher rates of receptive syringe sharing among those not having ever received an HIV-positive diagnosis and a lower likelihood of believing that condoms are needed when having sex with a casual partner. Conclusion: Although extensive HIV testing has alerted many PWID to their HIV-positive status, which is associated with less distributive syringe sharing and higher likelihood of condom use, substantial risk for parenteral and especially sexual HIV transmission remains. More active prevention programs will be required to control the heterosexual spread of HIV.