Recent seroprevalence studies have shown alarming rates of HIV infection among severely mentally ill men and women in large urban areas, and HIV behavioral epidemiology research indicates that a substantial proportion of seriously mentally ill adults engage in activities that increase their vulnerability to HIV/AIDS. In this paper the research literature on HIV prevention interventions is reviewed including reports that have described HIV prevention programs, studies that have used uncontrolled pre- and postintervention methods to evaluate risk reduction interventions, and those that have used rigorous randomized designs and examined risk behavior change. Collectively, these studies show that intensive, small-group interventions that target a variety of risk-related dimensions - including knowledge, attitudes, and motivations, and behavioral and cognitive skills - can produce at least short-term reductions in high-risk sexual behavior among the severely mentally ill. A number of gaps in the research literature are identified including the need to: (a) better tailor interventions to risk situations encountered by the mentally ill; (b) develop gender-tailored interventions; (c) examine and implement HIV prevention programs so they help persons sustain behavior change; (d) explore one-on-one counseling and community-level intervention methods; and (e) develop risk reduction interventions for already-seropositive individuals. implications for service provision are discussed. (C) 1997 Elsevier Science Ltd.