The objectives of this study were first, to identify psychosocial and medical service utilization factors associated with unprotected sex with HIV-negative or unknown serostatus partners among persons living with HIV/AIDS, and second, to identify risk behaviours associated with HIV medical service use. We assessed 244 HIV-positive participants in an HIV intervention targeting drug users (1997-99). Fifty-seven per cent of HIV-positive participants reported unprotected sex within the past 90 days, 16.4% with serodiscordant partners. Odds of risky sex were lower among those currently receiving HIV medical care (odds ratio (OR)=0.36), and were greater among females (OR=2.6), those having friends with lower norms of condom use (OR=3.3), and those having a main sexual partner (OR=6.2). Lower odds of receiving HIV medical care were associated with current drug use (OR=0.33), sharing drugs with a sex partner (OR=0.27), and exchanging sex for drugs or money (OR=0.24). Findings suggest the importance of community-based HIV prevention intervention targeting HIV-positive drug users not recovery HIV medical care.