OBJECTIVE: To examine the proportion of migrants from Sub-Saharan Africa entering the Swiss HIV Cohort Study (SHCS) and to compare these participants with participants from Northwestern Europe for access to antiretroviral therapy, progression to AIDS and survival. DESIGN: Prospective national cohort study of HIV-1-infected adults from seven HIV centres in Switzerland. METHODS: Trends in the proportion of participants from Sub-Saharan Africa were followed in 11 872 HIV-infected adults entering the SHCS from 1984 to 2001. Survival methods were used to compare uptake of antiretroviral therapy, survival and progression to AIDS in the 2684 participants from Sub-Saharan Africa and Northwest Europe enrolled from 1997-2001. RESULTS: There was a steady increase in the proportion of Sub-Saharan African participants over time, reaching 11.9% in 1997-2001. These participants were more likely to be younger, female, to have been infected by heterosexual intercourse and had lower CD4 cell counts at presentation. There were no differences between Sub-Saharan Africans and Northwest Europeans in uptake of triple antiretroviral therapy, progression to AIDS or survival up to 48 months after starting treatment. Tuberculosis was the most frequent AIDS-defining event in Sub-Saharan African patients. CONCLUSIONS: There is no evidence that access to potent antiretroviral therapy is influenced by geographic origin of participants. The prognosis of Sub-Saharan African patients on triple therapy is equivalent to that of Northwest European patients. Future research should address wider issues about access to specialist health services for HIV-infected people from Sub-Saharan Africa.