OBJECTIVE: The paper reviews data on drug use in relation to the spread of human immuno-deficiency virus and AIDS in South America and the Caribbean. METHODS: Information was gathered by thoroughly reviewing major bibliographic databanks, web sites of international institutions and regional networks working with substance misuse or human immunodeficiency virus and AIDS, and abstracts from conferences and meetings. RESULTS: Although some gaps remain, a growing body of evidence documents the significant role of injected cocaine in the Brazilian and Southern Cone epidemics. The Caribbean and the Andean areas have thus far been spared in large part from the spread of injection drug use and its consequences, but the situation has been changing in Southern Cone countries towards a higher prevalence of harmful injection habits. Additional challenges have been posed by the increasing availability of heroin in the Andean Area and the abuse of crack cocaine and its impact on the sexual transmission of human immunodeficiency virus in many cities. Harm reduction strategies have been established in most areas of Brazil and are gaining momentum in Argentina. Other countries in the Region still face serious limitations due to restrictive legislation and lack of broader support. CONCLUSION: Greater participation of Latin American and Caribbean countries in research protocols and continued debate on both successful and failed experiences should be encouraged in order to minimize existing barriers to the full adoption of effective measures to curb the human immunodeficiency virus and AIDS epidemic in this Region.