Thirty serum samples of patients with early leptospirosis from whom cultures of leptospira were positive were tested by dot-enzyme linked immunosorbent assay (dot-ELISA) and microscopical agglutination test (MAT). The results showed that the positive rate of dot-ELISA (40%) was higher than that of MAT (13.3%). One-hundred and ninety-eight serum samples from patients with clinical diagnosis of early leptospirosis were tested by dot-ELISA, MAT and blood culture. The results showed that the positive rate of dot-ELISA (64.6%) was higher than that of blood culture (15.2%) and MAT (14.1%). The longer the time of the illness, the lower the positive rate of the blood culture. However, the positive rate of dot-ELISA was stable in different stages of the illness.