The indirect immunoperoxidase method was evaluated in 265 biopsies with the purpose of increasing the sensitivity of the diagnostic histopathology of tegumentary lesions caused by subspecies of the Leishmania braziliensis complex. A diagnosis of leishmaniasis was established by parasitological methods (181) or clinical criteria (12) in 193 patients (72.8%). In the latter group of confirmed cases standard histochemistry and immunoperoxidase were compared with direct examination of tissue scraping and culture of lesion aspirates. The detection and localization of amastigotes was more efficient using the immunoperoxidase method (61.3%) than conventional histopathology with hematoxilin and eosin (34.6%) or direct examination of tissue scraping (43.9%). However, culture of lesion aspirates was the most sensitive procedure (89.8%). The efficiency of the immunoperoxidase method was greater in recent lesions, being positive in 75% of cases with less than 3 months evolution, while 55.6%, 37.5%, and 21.1% of cases with lesion evolution of 3-5.9, 6-11, and 12 months or greater, respectively, were positive. The combined use of the direct examination of lesion scraping and immunoperoxidase applied to histological sections of the biopsy from the lesion border allowed an etiologic diagnosis of 72% of confirmed cases. Cross-reactivity was observed with Paracoccidioides braziliensis but not with Mycobacterium leprae, Sporothrix schenckii, or Histoplasma capsulatum.