The objective of this study was to analyze the association between bacterial vaginosis (BV) and squamous intraepithelial lesion (SIL). Pap smears were analyzed to verify the presence of BV and SIL. One hundred and ten women with SIL comprised the study group, while 110 women with no cytological abnormalities served as controls. BV was similarly present in women of both groups: 18% of women with SIL and 12% of women without SIL. Results were also similar when the grade of SIL was taken into consideration. BV was detected in 16% of women with low-grade SIL and in 12% of women in the control group, while a higher rate of BV (33%) was found among women with high-grade SIL in comparison to the controls (12%). This difference, however, was not statistically significant. BV tended to be more common among women with high-grade SIL than in women with no cytological abnormalities.