Although support groups for HIV-seropositive persons are a potential source of emotional support and information, there has been little assessment of such groups as to their role in changing risk behaviour for transmission. The present study combines observations from over 52 group sessions with baseline and follow-up interview data to assess changes in sex and drug behaviour among seropositive drug users participating in an ongoing group for African Americans. The sample of 100 adults was recruited from drug treatment centres and from the community in Atlanta, Georgia. At the 6-month interview, frequency of group attendance was associated mainly with healthier drug behaviour, the topic most frequently discussed by members. Findings suggest that training for support group facilitators needs to target two areas for technology transfer: successful strategies for reducing both high-risk sex and drug behaviour and methods for introducing these behavioural change tools into a setting designed for socio-emotional support. We conclude that community support groups are an untapped opportunity for low-cost prevention services.