Background: To study the prevalence of abnormal anal cytology by Papanicolaou (Pap) technique in HIV-infected women who attended a HIV clinic at Prapokklao Hospital, Chanthaburi, Thailand. Materials and Methods: HIV-infected women who attended a HIV clinic at Prapokklao Hospital from March 2013 to February 2014 were recruited for anal Pap smears. Participants who had abnormal results of equally or over "abnormal squamous/glandular cells of undetermined significance" (ASC-US) were classified as abnormal anal cytology. Results: A total of 590 anal Pap smears were performed at HIV clinic of Prapokklao Hospital during the study period. There were only 13 patients who had abnormal Pap tests, which were: 11 ASC-US and 2 HSIL (high grade squamous intraepithelial lesion). The prevalence of abnormal anal Pap smears in HIV-infected women who attended HIV clinic at Prapokklao Hospital was 2.2 percent. Percentage of high risk HPV in patients who had abnormal Pap test was 88.9 (8/9). Conclusions: The prevalence of abnormal anal Papanicolaou smears in HIV-infected women who attended the HIV clinic at Prapokklao hospital was quite low in comparison to the earlier literature.