OBJECTIVE: To determine characteristics and clinical course of high-grade anogenital intraepithelial neoplasia (AIN) in human immunodeficiency virus (HIV)-infected women. STUDY DESIGN: HIV-positive women with biopsy-proven high-grade (II and III) vulvar (VIN), vaginal (VAIN) or perianal intraepithelial neoplasia (PAIN) were identified in the electronic databases of 2 colposcopy clinics. RESULTS: A total of 31 patients were identified from 1992 to 2007, of which 30 had a mean follow-up of 47.7 months (SD = 46.0; range, 2.6-166.2). Of the patients, 77.4% had VIN, 12.9% VAIN and 9.7% PAIN at first diagnosis. Age at diagnosis of IN was 36.2 years (SD +/- 5.2; range, 23.5-47.0). Ninety percent of patients received antiretroviral therapy at first diagnosis of IN; 65% (13 of 20) of patients with a follow-up of > 2 years required a second treatment, and 2 developed invasive vulvar cancer (10%). CONCLUSION: AIN among HIV-positive women shows a high relapse rate despite treatment modality used and a substantial invasive potential.