Amphotericin B is an effective but toxic antileishmanial agent. Lipid-encapsulated amphotericin B should have a high therapeutic index for visceral leishmaniasis because reticuloendothelial cells, the sole site in which Leishmania is found, will phagocytize and concentrate the complex. Amphotericin B cholesterol dispersion (Amphocil; 2 mg/[kg.d] intravenously) was administered to 10 Brazilians with kala-azar for 10 days (cohort 1) and to 10 Brazilians with kala-azar for 7 days (cohort 2). All patients were successfully treated: 19 of the 20 patients were without visible parasites in the bone marrow; the mean time to afebrility was 4.2 days; spleen size regressed by a mean of 79% 2 months after therapy; and no patient had clinical or laboratory abnormalities by the end of 6-12 months of follow-up. Side effects were fever and chills accompanied by respiratory distress, but not nephrotoxicity, in children < 3 years of age.