The purpose of this study was to investigate the effectiveness and safety of palliative chemotherapy using S-1 alone. We clinically analyzed 8 oral squamous cell carcinoma patients showing a complete response(CR)to chemotherapy with S-1 alone. These patients received chemotherapy consisting of 2 weeks' administration, including 5-days' administration and 2- days' termination, following a 1-week rest. Adverse effects were observed in 4 patients. However, all of them were grade 1 toxicities. The average length of S-1 administration before achieving CR was 9. 8 ± 3. 1 weeks(3. 3 ± 1. 0 courses). Seven patients had a recurrence. The prognosis of this group was 5 deaths by local recurrence, and 1 death by lymph node metastasis. The average length of disease progression was 447. 4 ± 479. 5 days. Two patients, one who received surgery and the other who received irradiation after chemotherapy by S-1, are alive without tumors. The 1-year and 3-year disease-free survival rates were 100% and 37. 5%, respectively.