In this study, we evaluated the feasibility, efficacy and toxicity of concurrent chemoradiotherapy with S-1 (tegafur-gimeracil-oteracil potassium) for T2N0 glottic carcinoma. A total of 23 patients with T2N0 glottic carcinoma received chemoradiotherapy with S-1. Radiotherapy consisted of five daily fractions of 2 Gy per week, to a total median dose of 70 Gy. S-1 was administered 65 mg/m(2) per day for 4 weeks, beginning on the day therapy was started, followed by 2 weeks off the drug and twice a day until the end of radiotherapy. Initial local control rate of the primary tumor was achieved in all patients. The median follow-up period for all patients was 38 months. The 3-year local control rate was 95.4%. Regarding adverse reactions, grade 3 mucositis upon clinical examination, mucositis upon functional/symptomatic examination, dysphagia, hepatic toxicity and anemia were observed in 13, 2, 2, 1 and 1 patients, respectively. This chemoradiotherapy did not result in grade 4 acute toxicity or severe late toxicity. Chemoradiotherapy with S-1 was feasible, well tolerated and effective. This therapy is suggested as a possible regimen for improving local control of T2N0 glottic carcinoma.