A total of 273 serum specimens from different areas and sources were tested against Borrelia burgdorferi antigens by enzyme-linked immunosorbent assay method. Positive rates of serological reactions were 3% and 58% for healthy persons and syphilis patients, respectively. Obviously, there was a lot of cross-reaction in the venereal disease group. Meanwhile, positive rates were 3% and 13% in the sera collected from Taiwan and Orchid Island, respectively. This difference may reflect a less developed environment in the latter. Since reported cases of Lyme disease in Taiwan are rare, serologic tests are usually adapted for rapid diagnosis in common laboratories. As for disease confirmation, clinical observations, epidemiological data and exposure in an endemic area must also be considered.