Ten patients with mucosal lesions caused by American tegumental leishmaniasis were treated with pentamidine isethionate at the dose 4 mg/kg on alternate days by the intravenous route. The mean posology was 2,140 mg. Healing of the lesions occurred in 9 (90%) of the patients who completed treatment. There was no recurrence during a follow-up time of 1 to 24 months (mean, 7,7 months). One patient discontinued treatment before healing of the lesion because be developed diabetes mellitus. In 3 (30%) patients, blood exams showed increased urea and creatinine levels and leucopenia, which were corrected by increasing the interval between administrations of the drug. Pentamidine isethionate is efficient in bringing about cicatrization of the lesions but needs further evaluation in terms of its value in preventing recurrence.