The peroxidase-antiperoxidase (PAP) method was applied for identification of amastigotes of Trypanosoma cruzi in routinely prepared histological sections. The tissue specimens were obtained from patients with chronic Chagas' disease and from mice and dog with acute Chagas' disease. Specific rabbit antisera were produced against CL, Y and Ernane strains of T. cruzi and were used as primary reagents. Normal rabbit serum and phosphate buffered saline were used as negative controls and amastigotes within macrophages cultured from mice peritonium were used as positive controls. Positive staining was localized specifically in amastigotes in all the tissues treated with the antisera against the different strains of T. cruzi. The isolated or intracellular nests of amastigotes were easily identified in histological sections using the small or medium size magnifications of the microscope. The present method increases the probability of microscopic diagnosis of parasites in Chagas' disease and helps to prevent confusion of amastigotes with other morphologically similar infective agents.