The number of reported cases of Leptospirosis in Thailand has grown since 1996. Identification of major reservoirs and endemic areas is essential in surveillance of Leptospira species in Thailand. To assist in the effort of surveillance, a dipstick assay for detecting Leptospira antibodies in mammals was adapted from a human diagnostic assay and tested in a field trial in Thailand. Antibodies to Leptospira were detected in 18 of 60 wild rodents. Four of 9 culture positive rodents were positive by the dipstick assay. The proportion of sera positive for antibodies by dipstick was correlated with positive culture outcome using McNemar test for correlated proportions (0.83, P> 0.05). The dipstick assay was effective in detecting antibodies to Leptospira in mammals and may be useful in resource poor areas or under circumstances where the microagglutination test (MAT) is not practical.