To explore the relationship between vitamin A (retinol) deficiency and cervical squamous intraepithelial lesions (SILs) in human immunodeficiency virus (HIV)-infected women, we measured serum retinol concentrations in 1314 women enrolled in the Women's Interagency HIV Study and correlated the results with concurrent cervical cytology. At the baseline visit, 204 (15.5%) of the 1314 patients had retinol concentrations consistent with deficiency (<1.05 μmol/L). Analysis of Papanicolaou smears showed SILs in 216 (16.4%) of 1314 women. Cervical SILs were found to be associated with retinol concentrations <1.05 μmol/L (multivariate odds ratio [OR], 1.63; P = .04) in a multivariate model, which included human papillomavirus (HPV) status and markers of nutritional status and HIV disease stage. In the subset of women with genital HPV (n = 774), a multivariate analysis again revealed a significant independent association between retinol <1.05 μmol/L and cervical SILs (multivariate OR, 1.75; P = .02). Our findings suggest that retinol deficiency may contribute to the development of cervical SILs in HIV-infected women.