Background: Black women are more likely to have bacterial vaginosis (BV) than are non-Hispanic white women. We examined whether this disparity can be explained by racial differences in known BV risk factors. Methods: Nine hundred black and 235 white women were enrolled from five US sites. At baseline, structured interviews were conducted and vaginal swabs self-collected for Gram-stain and culture. Results: Black women were more likely than white women to have BV/intermediate vaginal flora. They also were more likely to be older, have lower educational attainment and family incomes, have a history of a sexually transmitted disease, and douche. After adjustment for demographic and lifestyle factors, blacks remained at elevated risk for BV/intermediate flora (OR 2.2, 95% CI 1.5-3.1). Blacks also were more likely to have specific BV-related vaginal microflora, as well as gonococcal or chlamydial cervicitis (OR 2.2, 95% CI 1.2-3.8) after adjustment for known BV risk factors. Conclusion: Risk factor differences did not explain the observed racial disparity in the occurrence of BV, BV-related microflora, or gonococcal or chlamydial cervicitis. These findings highlight our limited understanding of the factors accounting for the occurrence of bacterial vaginosis and cervicitis among black and white women.