We describe 40 HIV-seropositive patients who developed visceral leishmaniasis. All the patients lived in areas endemic for visceral leishmaniasis and belonged to groups at risk for AIDS. Twenty-three patients (57.2%) had definitive AIDS before or after diagnosis of leishmaniasis and 77.5% were classified as belonging to CDC group IV. Fever was present in 95% patients and enlargement of the liver and/or spleen in 92.5%. Lymphopenia was found in 78.3%, depression of the absolute number of CD4 lymphocytes in 90% and depression of the CD4 to CD8 ratio in all evaluated cases but leishmania antibodies were found in only 35.2%. Parasites were demonstrated in the bone marrow or liver in every case. Thirty patients (75%) showed an initial good response to antimonial drugs, although the leishmaniasis followed a chronic or relapsing course in 17 (42.5%). HIV-related mortality was 40%. A significant correlation was found only between the relapsing course of the disease and mortality. In a multivariate linear regression model, the relapsing course was the only variable that influenced mortality. Visceral leishmaniasis is an opportunistic disease that should be suspected in HIV-infected patients. We suggest that it should be included in the CDC group IV C-1 and considered as a disease indicative of AIDS.