['Anal carcinoma is being found in HIV-positive patients with increasing frequency. Most patients are treated with combined chemotherapy and radiation. It was our impression that HIV-positive patients do not fare as well as HIV-negative patients in terms of both response to and tolerance of therapy.', 'To test this hypothesis, we reviewed our experience with anal carcinoma and compared HIV-positive to HIV-negative patients by age, gender, sexual orientation, stage at diagnosis, treatment rendered, response to treatment, tolerance, and survival. From 1985 to 1998, 98 patients with anal neoplasms were treated. Seventy-three patients had invasive squamous-cell carcinoma (including cloacogenic carcinoma), and this cohort was analyzed. Thirteen patients were HIV positive and 60 were HIV negative.', 'The HIV-positive and HIV-negative groups differed significantly by age (42 vs. 62 years, P < 0.001), male gender (92 vs. 42 percent, P < 0.001), and homosexuality (46 vs. 15 percent, P < 0.05). There were no differences by stage at diagnosis or radiation dose received. Acute treatment major toxicity differed significantly (HIV positive 80 percent vs. HIV negative 30 percent; P < 0.005). Only 62 percent of HIV-positive patients were rendered disease free after initial therapy vs. 85 percent of HIV-negative patients (P = 0.11). Median time to cancer-related death was 1.4 vs. 5.3 years (P < 0.05). A survival model did not show age, gender, stage, or treatment to be independent predictors.'] Do hIV-positive patients with anal carcinoma have poorer treatment tolerance and outcome than HIV-negative patients?