Local hyperthermia induced by ultrasound was delivered two or three times weekly to twenty-eight lesions of acute cutaneous leishmaniasis in eighteen patients. Twenty-two lesions (78.5 percent) in thirteen patients resolved completely five to ten weeks after the start of treatment. Our results are explained by the thermosensitivity of the parasite and its inability to survive at supranormal temperatures. Ultrasound hyperthermia was tolerated by most of the patients. The results of this study indicate that topical heat is safe and effective for the treatment of patients with acute cutaneous leishmaniasis.