The therapeutic effect of the emetine hydrochloride alkaloid administered intralesionaly was compared with that of standard parenteral treatment with Glucantime® in outbred male hamsters experimentally infected with 4 x 103 amastigotes of Leishmania (Viannia) braziliensis. Both chemotherapeutic agents reduced significantly (P < 0.01) the average lesion sizes in experimental animals in comparison with those untreated. The alkaloid infiltration was found to be as effective as the antimonial injection for clinical resolution. The ultrastructural effects on the Leishmania parasites exposed to emetine were observed mainly in the inner cytoplasm, which appeared disorganized, pycnotic and with loss of morphological definition; however, any known emetine hydrochloride action mechanism factor could not be directly related with ultrastructure effects detected on leishmanial parasites. Smears, conventional histopathology, culture in NNN medium and indirect inmunoperoxidase method showed viable amastigotes in nodules and/or scars of all the evaluated hamsters 75 to 230 days after the end of treatment. These findings suggest that measurement of the size of cutaneous leishmanial lesions does not appear to be a valid criterion for evaluating the efficiency of chemotherapy in experimental LT. Detection of leishmanial parasites in the lesion scars, supports the hypothesis that man could be considered as an intradomiciliar reservoir. Recibido: 03-09-2000. Aceptado: 30-11-2000.