We have treated four Japanese patients with squamous cell carcinoma of the anal canal using concurrent chemoradiotherapy. The chemotherapy consisted of one or two cycles of mitomycin C 10 mg/m(2)/day (intravenous bolus injection) on day 1, and 5-fluorouracil 700 or 1,000 mg/m(2)/day (continuous intravenous infusion) on days 2-5 during radiotherapy. The total radiation dose was 40-54 Gy to the primary lesion. Acute grade 4 hematological toxicity was observed in one patient. These four patients have been alive and free of disease (follow-ups of 55, 14, 7 and 5 months, respectively), with excellent function of the anal sphincter after treatment. These results suggest that concurrent chemoradiotherapy is safe and effective for Japanese patients with squamous cell carcinoma of the anal canal.