The initial hypothesis of this study was that folate depletion is a risk factor for human papillomavirus infection and cervical epithelial cell abnormalities, including dysplasia. The prevalences of low erythrocyte folate levels (defined as < 140 ng/mL erythrocytes and determined by the growth of Lactobacillus) were measured in 250 University of California at Los Angeles students. Among oral contraceptive users, low erythrocyte folate was a risk factor for an abnormal cytologic smear in both benign atypia and squamous intraepithelial lesions. Odds ratios were statistically significant for biopsied women who did not have condyloma and for those who did not have squamous intraepithelial lesions but not for those with histologically confirmed intraepithelial lesions. Low erythrocyte folate was a risk factor for a positive Virapap result in oral contraceptive users. If the folate effects are causal, the findings suggest that erythrocyte folate levels should be higher in oral contraceptive users than in nonusers to protect against an abnormal cytologic smear.