We report three cases of anal canal squamous cell carcinoma treated with radiotherapy combined with S-1 and mitomycin C(MMC). During radiotherapy, MMC was administered as intravenous bolus injection at a dose of 10mg/m2 on day 1 and 29. S-1 was administered orally at a dose of 80mg/m2 on days 1-14 and 29-43. Total radiation doses ranged 55. 8-60 Gy to pelvic lesions. The rates of grade 3 toxicity were: neutropenia, 100%; leucopenia, 100%; anemia, 33. 3%; anorexia, 66. 7%. These adverse events were tolerated. All of the three cases showed complete response without recurrences. These results suggested that this treatment schedule was safe and effective for anal canal carcinomas.