['To assess the efficacy of topical 80% trichloroacetic acid (TCA) to treat internal anal high-grade squamous intraepithelial lesions (HSILs) in HIV-positive individuals.', 'All patients who attended the University of Pittsburgh Anal Dysplasia Clinic for treatment of biopsy-proven internal anal HSIL with topical TCA between July 1, 2009, and June 30, 2012, and who had 1 or more follow-up visits to assess treatment efficacy were included in the analysis. Recurrence of HSIL was assessed in July 1, 2013.', 'A total of 98 HSILs from 72 patients were treated, and 77 (78.6%) resolved to normal epithelium or low-grade SIL during follow-up. Forty-eight (49.0%) and 27 (27.6%) of lesions resolved with 1 and 2 TCA treatments, respectively, whereas 1 lesion (1%) each resolved with 3 and 4 TCA treatments. Twenty-one (21.4%) lesions in 20 patients remained without resolution after TCA treatments. These patients were offered an alternative treatment. During follow-up, 8 (15.1%) of 53 patients had a lesion that recurred at the index site (11/53 [20.8%], inclusive of adjacent lesions) and 17 patients had new lesions diagnosed.'] Is topical application of trichloroacetic acid efficacious for the treatment of internal anal high-grade squamous intraepithelial lesions in HIV-positive men?