The recommended treatment for cutaneous leishmaniasis is pentavalent antimony at a dosage of 20 mg/kg/day for 20 days. Some studies conducted in locales in which Leishmania is endemic have suggested that shorter courses of treatment may be as efficacious. We conducted a randomized, double-blind, placebo-controlled study of 10 versus 20 days of sodium stibogluconate (SSG) in United States military personnel who contracted cutaneous leishmaniasis while serving overseas; 19 patients received SSG for 10 days (and placebo for 10 days), and 19 patients received SSG for 20 days. Cure rates were 100% (19 of 19 patients) in the 10-day group and 95% (18 of 19 patients) in the 20-day group. Side effects were more common among patients who received 20 days of therapy. In this group of otherwise healthy young adults, SSG at a dosage of 20 mg/kg/day for 10 days appears to have been therapeutically equivalent and less toxic than the standard 20-day course.