Background and Objectives: Bacterial vaginosis (BV) is the most common cause of vaginal discharge in the world. The study aimed to estimate the prevalence and to identify risk factors associated with bacterial vaginosis. Methods: A cross-sectional study was conducted in Ouro Preto, Brazil, between February and December 2017. Three hundred and forty-one women aged 18 years or older, users of the Brazilian Unified Health System, participated in this study. Women who used oral or topical antibiotics in the four weeks prior to the sample collection and women who had undergone a total hysterectomy were excluded from the study. After signing the Informed Consent Form and filling out a questionnaire containing sociodemographic, behavioral and sexual data, the participants were directed to the collection room, where the nurse collected the samples for the preventive examination of the cervix and also two vaginal swabs. Vaginal swabs and cervical samples were analyzed for cytological abnormalities and BV using Gram staining and cytology. Pathogens causing sexually transmitted infections (STIs) were identified by Polymerase Chain Reaction (PCR). For the analysis of the data, statistical package STATA version 10.0 was used. This study was approved by the Research Ethics Committee of the Federal University of Ouro Preto (UFOP). Results: During the study, 341 women were evaluated. The prevalence of BV using Gram staining (32.5% [CI95% 27.7=37.7%]) and cytology (27.7% [CI95% 23.0=32.8%]) was similar, however, the sensitivity of cytology was lower (77.8%). Risk factors associated with BV were smoking (IRR 1.5[CI95%: 1.1 = 2.1]), use of an intrauterine device (IRR 2.8 [CI95%: 1.2 = 6.5]), and past medical history of BV (IRR 1.5 [CI95%: 1.1 = 2.1]). Correlation between the presence of BV and Trichomonas vaginalis (TV) infection (r=0.24) was observed. Conclusion: The prevalence of BV was affected by life habits and was prevalent in women with TV. Thus, behavioral and social prevention approaches to women with diverse risk profiles may help mitigate TV/BV prevalence and recurrence of BV.