This phase I study is designed to determine the maximal tolerated dose and the dose-limiting toxicity of docetaxel with cisplatin and concurrent radiotherapy in patients with unresectable locally advanced gastric adenocarcinoma.Docetaxel was given once a week with the dosage escalated from 5 mg/m 2 to 15 mg/m 2 in increments of 2.5 mg/m 2 . Cisplatin were administered at 20 mg/m 2 once a week. Radiotherapy was delivered to 50.4Gy at 1.8Gy/day. At least three patients were enrolled at each level. The maximal tolerated dose (MTD) and dose-limiting toxicity (DLTs) was determined. The DLTs were defined as grade 3 or 4 hematologic and nonhematologic toxicity.Twenty-one patients with locally advanced gastric adenocarcinoma were enrolled. Grade 1-2 neutropenia and nausea/ vomiting were the most common side effects. The first DLT (grade-3 neutropenia) was observed in one of three patients at 12.5 mg/m 2 docetaxel. Three more patients were enrolled, but DLT was not observed and 6 patients were enrolled into 15 mg/m 2 group, DLT occurred in 3 patients (1 Grade 3 neutropenia, 1 Grade 4 neutropenia and 1 Grade 3 nausea/vomiting). Overall tumor response rate was 66.7% with 28.6% complete and 38.1% partial response.In conclusion, the MTD of docetaxel was 15 mg/m 2 , and the recommended dose of docetaxel for Phase II study was 12.5 mg/m 2 weekly. The docetaxel and cisplatin with concurrent radiotherapy were tolerable and feasible in treating locally advanced gastric adenocarcinoma.