We performed a systematic review and meta-analysis of the association between sexual risk factors and bacterial vaginosis (BV). Forty-three studies reported new or multiple sexual partners and condom use relative to prevalent, incident, or recurrent BV. The summary estimate of the relative risk for the association between BV new or multiple male partners was 1.6 (95% confidence interval, 1.5-1.8), between BV and any female partners was 2.0 (95% confidence interval, 1.7-2.3), and between BV and condom use was 0.8 (95% confidence interval, 0.8-0.9). This review is the first to summarize available observational data for BV. It shows that BV is significantly associated with sexual contact with new and multiple male and female partners and that decreasing the number of unprotected sexual encounters may reduce incident and recurrent infection. Investigation of sexual transmission of BV is limited by the absence of a clear microbiological etiology; however, we have shown that the epidemiological profile of BV is similar to that of established sexually transmitted infections.