In an 8-month period nine patients with human immunodeficiency virus (HIV) infection were diagnosed as having visceral leishmaniasis; all diagnoses were based on cultures (eight from bone marrow and one from the skin). Visceral leishmaniasis developed before full-blown acquired immunodeficiency syndrome (AIDS) in seven patients and at the same time as or after AIDS in the other two patients. Three patients had a history of leishmaniasis. Clinical manifestations and laboratory findings were atypical. Leishmania species were cultured from samples taken from all patients; however, six patients had an insignificant antileishmanial antibody titer and Leishmania amastigotes were not seen in their bone marrow smears. Four isolates were identified by isoenzyme analysis as Leishmania donovani infantum. Five patients died, including two patients who had completed at least one 3-week course of therapy with N-methylglucamine antimoniate. Screening should be done for visceral leishmaniasis in patients with HIV infection who live or travel in areas where the disease is endemic. The diagnosis of visceral leishmaniasis may frequently be missed if cultures are not done.