Twenty-three patients from Rio de Janeiro, Brazil-an area of Leishmania (Viannia) braziliensis transmission-were randomly assigned to receive either a high dose (20 mg/kg/day) of antimony or a lower one (5 mg/kg/day) in a 30 days series. The two treatment regimens showed similar responses. In 10 out of 12 patients receiving a dose of 5 mg/kg/day and 9 out of 11 patients with a dosage of 20 mg/kg/day a complete epithelization was noted by the end of treatment. In addition patients were followed for up to 7 years. No reactivation or development of mucosal lesions were observed in both groups during the extensive follow-up. We think that a low dosage of antimony could be equally effective than a higher one, at least in the presence of the clinical picture usually seen in Rio de Janeiro.