The expansion of AIDS treatment initiatives in resource-poor settings provides an opportunity for integrating mental health care into these programs. This systematic review of the literature on HIV and mental illness in developing countries examines the mental health risk factors for HIV, mental health consequences of HIV, psychosocial interventions of relevance for HIV-infected and affected populations, and highlights the relevance of these data for HIV care and treatment programs. We reviewed seven studies that measured the prevalence of HIV infection among clinic and hospital-based populations of people with mental illness or assessed sexual risk behavior in these populations; 30 studies that described the mental health consequences of HIV infection; and two reports of psychosocial interventions. The review demonstrates the need for methodologically sound studies of mental health throughout the course of HIV, including factors that support good mental health, and interventions that employ identified variables (e.g. coping, family support) for efficacy in reducing symptoms of mental illness. Promising intervention findings should encourage investigators to begin to study the implementation of these interventions in HIV service settings.