One hundred and twenty patients with localized cutaneous leishmaniasis were randomly allocated to receive tablets of dapsone (100 mg) or matching placebo tablets every 12 h for 6 weeks. No topical medication was used. Demonstration of Leishmania from skin lesions by the slit smear technique was mandatory for inclusion. Before, periodically during, and one month after completion of therapy an overall clinical assessment, haemoglobin determination, leucocyte count, and liver function tests were performed. 49 patients (82%) of those receiving dapsone were assessed as cured by clinical and parasitological criteria. Oral dapsone has certain advantages over other current forms of treatment: it is economical and widely available in countries where cutaneous leishmaniasis is common, and it is effective by mouth and well tolerated.