This study is a retrospective analysis evaluating the efficacy and toxicity of combination chemotherapy with S-1 and oxaliplatin (SOX) as first-line treatment in elderly patients with advanced gastric cancer. One hundred and twenty-nine patients with recurrent or metastatic gastric adenocarcinoma were treated with SOX; S-1 (40-60 mg depending on patient's body surface area) was given orally, twice daily on days 1 to 14 followed by a 7-day rest period, 130 mg/m(2) oxaliplatin was given as an intravenous infusion over 2-hours on day one. The cycle was repeated every three weeks. All of the patients were older than 65 years. Among 129 patients enrolled, nine patients could not be evaluated for responses because of the absence of any measurable lesions or early discontinuation of therapy. Assessment of the response of 120 patients was made. The overall objective response rate was 54.2 % (95 %CI, 45.3-63.1 %), with three complete responses and 62 partial responses. The disease control rate was 80.8 % (95 %CI, 73.8-87.8 %). The median follow-up period was 23 months (range, 5-42 months). The median time to progression was 6.9 months (95 %CI, 5.5-8.3 months) and the median overall survival was 12.8 months (95 %CI, 11.4-14.2 months). The one-year survival rate was 57.5 % (95 %CI, 48.7-66.3 %). In 129 patients assessed safety, grade 3 and 4 toxicities included leucopenia (20.9 %), neutropenia (24.0 %), anemia (10.9 %), thrombocytopenia (10.1 %), anorexia (3.1 %), peripheral neurotoxicity (15.5 %), and fatigue (12.4 %). No treatment-related deaths occurred. Combination chemotherapy with SOX offers an effective, safe and well-tolerated regimen for elderly patients with advanced gastric cancer.