In central European states, rates of HIV among injection drug users (IDUs) have been low although Hepatitis C (HCV) infection is widespread. The goal of our study was to assess HIV infection, risk perceptions and injecting equipment sharing among IDUs in Budapest, Hungary. Altogether 150 IDUs were interviewed (121 structured interviews between 1999 and 2000 and 29 ethnographic interviews between 2003 and 2004). The majority of them injected heroin (52% and 79%) and many injected amphetamines (51% and 35%). One person tested positive for HIV. Two thirds (68%) shared injecting equipment (syringes, cookers and filters). Some participants said they shared syringes because they were not carrying them for fear of police harassment and that they reused filters as a backup drug supply. In multivariate analysis, sharing of injecting equipment was associated with higher perceived susceptibility to HIV/AIDS, lower self-efficacy for sterile equipment use, higher motivation to comply with peer pressure to use dirty injecting equipment and with having a criminal record. The high levels of injecting risk-behaviors found in this study are a cause for serious concern. Interventions for HIV-prevention need to address not only sharing syringes but also sharing and reusing of other injecting equipment and drug filters.