OBJECTIVE: To estimate the frequency of abnormal Pap and human papillomavirus (HPV) positivity among human immunodeficiency virus (HIV)-seropositive and -seronegative women who have sex with women (WSW). METHODS: Pap and HPV DNA polymerase chain reaction tests were obtained every 6 months from women in a US cohort of HIV-seropositive and -seronegative women. Women who have sex with women were women reporting no male and at least 1 female sex partner for 5 years. They were frequency matched 1:5 to women reporting sex only with men (WSM) and assessed using multivariable generalized estimating equation logistic regression models. RESULTS: Paps at study entry were abnormal in 12 (21%) of 49 HIV-seropositive WSW, 151 (64%) of 245 HIV-seropositive WSM, 3 (9%) of 24 HIV-seronegative WSW, and 16 (11%) of 120 HIV-seronegative WSM. Human papillomavirus was found at entry in 18 (42%) HIV-seropositive WSW, 109 (52%) HIV-seropositive WSM, 6 (27%) HIV-seronegative WSW, and 13 (13%) HIV-seronegative WSM. After controlling for HIV serostatus and CD4 count, WSW had marginally lower odds than WSM of Pap abnormality (odds ratio = 0.59, 95% confidence interval = 0.33-1.03) and of HPV (odds ratio = 0.53, 95% confidence interval = 0.32-0.89). After controlling for partner's gender, HIV seropositivity and lower CD4 count were associated with any HPV, oncogenic HPV, any abnormal Pap result, and high-grade squamous intraepithelial lesion or worse (p < .0001 for all). CONCLUSIONS: Although risks for abnormal Pap and HPV are modestly lower in WSW than in WSM, both are common in HIV-seropositive women regardless of sexual preference. Both WSW and WSM should be screened similarly.