Cancer-associated human papillomavirus (HPV) types are detected in genital warts removed from immunosuppressed individuals more commonly than from those occurring in otherwise healthy individuals. The prognosis of genital warts containing cancer-associated HPV types is not known. Because it is assumed that genital warts are benign lesions, they are usually treated by destructive therapies without prior knowledge of histopathology. The aim of the present study was to determine whether genital warts from individuals with or without human immunodeficiency virus (HIV) contain high-risk HPV types or areas of dysplasia. The study design was a nonrandomized analysis of genital warts removed by excision biopsy from 15 HIVinfected patients and 15 HIV-negative patients. The tissue was analyzed for HPV DNA by hybrid capture, and microscopic sections of each biopsy were examined for areas of dysplasia. Genital warts from HIV-infected patients contained cancer-associated (''high risk'') HPV types in 9 of 15 cases, including 1 that contained only a high-risk type. High-grade dysplastic abnormalities were present in 2 of the 15 lesions from this group, both of which contained high-risk HPV types. Four genital warts removed from HIV-negative patients contained high-risk HPV types, but none contained dysplastic abnormalities. It is concluded that genital warts from HIVinfected patients often contain high-risk HPV types. Such lesions may exhibit dysplastic changes. The frequency of dysplastic changes in genital warts from HIV-infected patients is not known. Biopsy of genital warts may be indicated prior to additional therapy in HIV-infected patients, and surgical removal should be consid-ered as a preferred treatment option in these patients.