When the enzyme-linked immunosorbent assay for the detection of specific immunoglobulin M class antibodies was applied to paired saliva and serum samples from 40 patients with leptospirosis, positivity was 87.5% and 100%, respectively. No positive result was obtained with any saliva or serum sample from 60 individuals used as controls. These results suggest the alternative use of saliva for diagnosis and for epidemiological studies of human leptospirosis.