Bacterial vaginosis (BV), a condition of altered vaginal flora, is associated with various adverse reproductive health outcomes. We evaluated the association between diet and the presence of BV in a subset of 1521 women (86% African-American) from a larger study of vaginal flora. Participants completed the Block Food Questionnaire and clinical assessments and self-report measures of sexual and hygiene behavior. A total of 42% of the women were classified as having BV (Nugent score > or = 7). Severe BV (Nugent score > or = 9 and vaginal pH > or = 5) was present in 14.9% of the women. BV was associated [adjusted OR (AOR)] with increased dietary fat (1.5, 1.1-2.4) after adjusting for other energy nutrients and behavioral and demographic covariates. Severe BV was associated with total fat (2.3, 1.3-4.3), saturated fat (2.1, 1.2-3.9), and monounsaturated fat (2.2, 1.2-4.1). Energy intake was only marginally associated (P = 0.05) with BV (1.4, 1.0-1.8). There were significant inverse associations between severe BV and intakes of folate (0.4, 0.2-0.8), vitamin E (0.4, 0.2-0.8), and calcium (0.4, 0.3-0.7). We conclude that increased dietary fat intake is associated with increased risk of BV and severe BV, whereas increased intake of folate, vitamin A, and calcium may decrease the risk of severe BV.