We studied the relationships of selected microbial, clinical, demographic, and behavioral variables to mucopurulent cervicitis in two clinical settings, a sexually transmitted disease clinic and a student health clinic. From each clinic, we studied a group of women referred for suspected mucopurulent cervicitis and a representative sample of other women attending the clinic. After the women were stratified by patient group and summary odds ratios for all groups were obtained, mucopurulent cervicitis was most strongly associated with the isolation of Chlamydia trachomatis; other variables associated with mucopurulent cervicitis included the isolation of Ureaplasma urealyticum, Gardnerella vaginalis, and Trichomonas vaginalis, the presence of serum antibody to C. trachomatis, the clinical diagnosis of bacterial vaginosis, and oral contraceptive use (positive associations) or isolation of yeast (negative association). After adjustment for cervical culture results for C. trachomatis, mucopurulent cervicitis was positively associated with oral contraceptive use (p = 0.02) and isolation of U. urealyticum (p = 0.02) and negatively associated with isolation of yeast (p = 0.03). Among women with a positive cervical culture for C. trachomatis, isolation of U. urealyticum was significantly associated with mucopurulent cervicitis, while among the subgroup of women with a negative cervical culture for C. trachomatis and positive serum antibody to C. trachomatis, oral contraceptive use was strongly associated with mucopurulent cervicitis. These results confirm that in both clinical settings C. trachomatis is the major cause of mucopurulent cervicitis. The roles of U. urealyticum, T. vaginalis, G. vaginalis, bacterial vaginosis, and oral contraceptive use in the etiology of mucopurulent cervicitis deserve further study.