BACKGROUND: Anal carcinoma, a common disease in HIV positive patients, is usually treated with chemoradiotherapy. Generally tolerance was poor before the availability of highly active antiretroviral therapies. We report our experience of treating anal carcinoma in the era of new antiviral drugs. PATIENTS AND METHODS: Between 1997 and 2001, nine men on highly active antiretroviral therapies with good immune status before chemoradiotherapy received concomitant chemoradiotherapy consisting of 5-fluorouracil and cisplatinum, and high-dose radiotherapy (60- 70 Gy) for anal carcinoma. Six cancers were Stage I, two were Stage II, and one was Stage III. CD4? cell counts were < 200/ml for four patients, between 200/ml and 500/ml for four, and > 500/ml for one. RESULTS: All patients received the planned dose of radiation (≥ 60 Gy). The chemotherapy dose was reduced 25 percent in six patients. Overall treatment time was 58 days. Grade 3 hematologic or skin toxicity occurred in four patients. No association was observed between high-grade toxicity and CD4? cell count. None of the patients developed opportunistic infections during follow-up. Eight patients were disease-free after a median follow - up of 33 months. Among them, four had no or minor anal function impairment at the last follow-up visit. One patient with T4N2 disease relapsed locally one year after treatment and underwent salvage abdominoperineal excision. CONCLUSION: Highdose chemoradiotherapy for anal carcinomas is feasible with low toxicity in HIV- positive patients treated with highly active antiretroviral therapies. Local control is similar to that obtained for HIV-negative patients. BACKGROUND: Anal carcinoma, a common disease in HIV positive patients, is usually treated with chemoradiotherapy. Generally tolerance was poor before the availability of highly active antiretroviral therapies. We report our experience of treating anal carcinoma in the era of new antiviral drugs. PATIENTS AND METHODS: Between 1997 and 2001, nine men on highly active antiretroviral therapies with good immune status before chemoradiotherapy received concomitant chemoradiotherapy consisting of 5-fluorouracil and cisplatinum, and high-dose radiotherapy (60-70 Gy) for anal carcinoma. Six cancers were Stage I, two were Stage II, and one was Stage III. CD4? Cell counts were <200 / ml for four patients, between 200 / ml and 500 / ml for four, and> 500 / ml for one. the planned dose of radiation (≥ 60 Gy). The chemotherapy dose was reduced 25 percent in six patients. Overall treatment time was 58 days. Grade 3 hematologic or skin mass occurred in four patients. No association of observed between high-grade toxicity and CD4? cell count. None of the patients developed opportunistic infections during follow-up. Eight patients were disease-free after a median follow - up of 33 months. Among them, four had no or minor anal function impairment at the last follow-up visit. One patient with T4N2 disease relapsed one one year after treatment and underwent salvage abdominoperineal excision. CONCLUSION: Highdose chemoradiotherapy for anal carcinomas is feasible with low toxicity in HIV-positive patients treated with highly active antiretroviral therapies. Local control is similar to that obtained for HIV-negative patients.