In order to evaluate the reliability of immunoperoxidase technic (IP) for immuno-deposits in frozen renal tissue, a single blind study was done comparing it with immunofluorescent technic (IF). Fifty renal biopsies were studied. Ten there were no deposits by IF or IP. In 40 of them the results showed the same specificity and greater intensity for IP. There were 25 cases with IgG, 22 with IgM, 9 with IgA, 3 with Clq, 27 with C3 and 3 with HbsAg. We concluded that IP can be used in place of IF for detection of the immune deposits in renal biopsies and that it offers an easier observation than the later.