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. 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. 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. 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.