Anal cancer is a rare disease. Nevertheless, it may be a reason for concern among groups in which its incidence is increasing: those who engage in anoreceptive intercourse, promiscuous persons, and those with sexually transmitted infections (HPV and HIV). The aim of this study was to evaluate the prevalence of abnormal anal cytology in women infected with HIV seen at Hospital de Clínicas de Porto Alegre, Brazil. A cross-sectional design was used. Anal smear screening was offered to all women infected with HIV seen at the hospital's outpatient sexually transmitted infections clinic from March 2006 to March 2008. A total of 184 patients were thus enrolled. Only patients who gave written consent were included in the study. The prevalence of abnormal anal cytology was 14.1% (26 patients). Twenty-two patients presented atypical squamous cells of undetermined significance, and four exhibited low-grade intraepithelial neoplasia. Initially, abnormal anal cytology was significantly associated with age, number of pregnancies, smoking, abnormal cervical cytology, CD4⁺ < 200 cells/mm³ and hepatitis C co-infection. After adjustment, only CD4⁺ < 200 cells/mm³ and smoking were found to increase the risk of altered anal cytology. The anal Pap method described is simple and can be used for screening in cohorts of HIV-positive women who are at risk of developing anal carcinoma, mainly those with CD4⁺ counts <200 cells/mm³ and smokers.