Squamous epithelial cells are susceptible to infection by the human papillomavirus. Infection of squamous epithelium with oncogenic human papillomavirus types is associated with development of dysplasia and potential malignant transformation. Historically, cervical cancer has been the most prevalent human papillomavirus–induced squamous neoplasia. However, because of widespread screening via Pap smear testing, rates of cervical cancer in the United States have decreased dramatically during the past 50 years. Rates of anal cancer, in contrast, have doubled during the past 30 years. The groups at highest risk for development of anal cancer are men who have sex with men, HIV-positive patients, and patients immunosuppressed as a result of solid-organ transplantation. By detecting dysplasia before it develops into invasive cancer, anal Pap smears may be a potentially useful screening tool for anal cancer, particularly in individuals known to be at increased risk. However, at this time, sufficient data supporting the benefit of anal Pap smear screening are lacking. With insufficient evidence, no national health care organizations currently recommend the use of anal Pap smears as a routine screening test, even among high-risk groups.