OBJECTIVES: The purpose of this study was to investigate the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium, in women attending a sexually transmitted disease (STD) clinic, as well as the frequency of coinfections, and relationship of each organism to cervicitis. METHODS: In this cross-sectional study of 324 women attending Baltimore City STD Clinics, C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium were detected using nucleic acid amplification tests. Demographic characteristics and risk factors were ascertained. RESULTS: Overall prevalence of infection with C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium was found to be 11.1%, 4.6%, 15.3%, and 19.2%, respectively. Prevalence in women with cervicitis was 15.8%, 6%, 18.9%, and 28.6% for C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium, respectively. Percentages of coinfections were high. C. trachomatis and M. genitalium were significantly associated with cervicitis in univariate analysis, but only M. genitalium was significantly associated with cervicitis (AOR: 2.5) in multiple logistic regression models. CONCLUSION: Knowledge of the statistical association of M. genitalium with cervicitis in this study increases the need for further confirmation of the etiologic significance of this organism with cervicitis in more diverse populations. The high prevalence merits more study and may have implications for diagnosis and treatment of cervicitis.