An enzyme-linked immunosorbent assay (ELISA) for the detection of immunoglobulin M (IgM) antibodies in human leptospirosis was evaluated. From the results obtained in this study, it may concluded that the IgM-ELISA is a suitable technique not only for the detection of low levels of antibody, but also for measurement of non-agglutinating antibodies undetectable by means of microscopic agglutination test.