OBJECTIVE: To study how frequency, recentness, and reason for douching impact bacterial vaginosis-related vaginal microflora and the occurrence of cervical pathogens. Douching has been linked to bacterial vaginosis as well as to chlamydial cervicitis in some, but not all, studies. METHODS: A total of 1200 women at high risk for sexually transmitted infections were enrolled from five clinical sites around the United States. Cross-sectional, structured interviews were conducted and vaginal swabs were self-obtained for Gram stain, culture, and DNA amplification tests for Neisseria gonorrhoeae and Chlamydia trachomatis. RESULTS: Douching at least once per month was associated with an increased frequency of bacterial vaginosis. Those who douched recently (within 7 days) were at highest risk [odds ratio (OR) 2.1, 95% confidence interval (CI) 1.3, 3.1]. Douching for symptoms (OR 1.7, 95% CI 1.1, 2.6) and for hygiene (OR 1.3, 95% CI 1.0, 1.9) both related to bacterial vaginosis risk. The associations between douching and Gardnerella vaginalis, Mycoplasma hominis, and lack of hydrogen peroxide-producing lactobacilli were similar to those between douching and bacterial vaginosis. Gonococcal or chlamydial cervicitis was not associated with douching. CONCLUSION: Douching for symptoms or hygiene, particularly frequent or recent douching, was associated with bacterial vaginosis and bacterial vaginosis-associated vaginal microflora, but not with gonococcal or chlamydial cervicitis. © 2002 by The American College of Obstetricians and Gynecologists.