ObjectiveTo evaluate the association between vaginal douching and cervicalChlamydia trachomatisinfection.MethodsWe analyzed cross-sectional data from a study conducted at Group Health Cooperative of Puget Sound, a nonprofit health maintenance organization in western Washington state. Participants were nonpregnant women Group Health enrollees between the ages of 18 and 34 years who were attending two primary care clinics either for nonurgent visits, primarily routine preventive health visits, or in response to an invitation from the study. Before the clinical examination, all completed a self-administered survey assessing demographic and behavioral characteristics, including the timing, frequency, products used, and reasons for douching. Chlamydial infection was ascertained via cell culture isolation ofC trachomatisfrom endocervical specimens obtained at the same visit.Results Chlamydia trachomatiswas isolated from cervical cultures in 58 (3.4%) of 1692 study participants. Women who reported douching in the 12 months before their clinic visit had an increased likelihood of chlamydial infection compared with women who did not douche (prevalence odds ratio [OR] 2.29, 95% confidence interval [CI] 1.22, 4.30, after adjusting for confounding factors). The likelihood was higher for women who reported douching more often: OR 2.60 (95% CI 1.29, 5.24) for women who douched one to three times per month, and OR 3.84 (95% CI 1.26, 11.70) for those douching four times or more per month. These associations were slightly stronger when women who reported douching because of an infection were excluded from the analysis.Conclusion:These results support the hypothesis that vaginal douching predisposes to acquisition of cervical chlamydial infection and are compatible with previous studies that report associations between douching and sequelae of chlamydial infection, including pelvic inflammatory disease, ectopic pregnancy, and infertility.