Risk factors for anal cancer include anal intercourse and infection with multiple strains of human papillomavirus, the causative agent of anal precancerous dysplasia. Several recent studies have shown that HIV-seropositive gay men are at greater risk for anal dysplastic lesions than seronegative gay men. Moreover, the risk for detection and progression of dysplastic lesions grows as the CD4+ cell count declines. A surgeon with a practice that includes gay men referred for anorectal disease presents data regarding the high prevalence of anal dysplasia in his patients.