Objectives: To characterize the distribution patte of biovars and serotypes of Ureaplasma urealyticum in normalhealthy women, sexually transmitted infections clinic clientsand in sex workers. Methods: We cultured cervical swabs taken from 261physical check-up clients, 599 STI clinic outpatients and 98sex workers using commercial selective medium. Somepositive cultures were further biotyped and serotyped byPCR.Results: (1) Biovar 1 of U. urealyticum (95.0%), especiallysingle infection of serotype 1, 3, and 6 of biovar 1, iscommonly found in healthy women. (2) U. urealyticum ismore commonly isolated in sex workers (90.8%) than inphysical check-up group (60.9%) and STI outpatients group(61.3%) (P＜ 0.001). (3) Biovar 2 infection of U. urealyticumis more prevalent in sex workers (28.1%) and STIoutpatients group (26.6%) than that in physical check-upgroup (4.9%) (P ＜ 0.001). (4) Mixed infection caused bymore than one serotype of U. urealyticum is increasing fromphysical check-up group (8.6%) to STI outpatients (12.4%)and to sex workers (23.9%) (P ＜ 0.01). (5) There is nostatistic difference in the distribution of serotype 1, 3, and 6of biovar 1 among these three groups (P=0.763). (6) ThePCR method described here is relatively simple, rapid andspecific for the biotyping and serotyping of biovar 1 of U.urealyticum.Conclusion: we should pay more attention to biovar 2and mixed infection than single infection of biovar 1 of U.urealyticum in clinic practice. PCR is a good method inbiotyping and serotyping.