We designed this phase I/II study of docetaxel-oxaliplatin combination chemotherapy to determine the dose-limiting toxicity (DLT), maximum tolerated dose and efficacy as a first-line treatment in patients with advanced gastric cancer. Patients with histologically proven, chemo-naive gastric adenocarcinoma were eligible. For the phase I part, three dose levels of oxaliplatin and docetaxel every 3 weeks were tested in a cohort of three patients for each level (respectively, 100 and 60 mg/m(2), 100 and 75 mg/m(2), 130 and 75 mg/m(2)). Patients were treated up to a maximum of nine cycles of oxaliplatin and docetaxel unless there was documented disease progression, an unacceptable adverse event, or withdrawal of consent. No DLT was observed at any of the three levels tested in the phase I portion. Therefore, oxaliplatin 130 mg/m(2) and docetaxel 75 mg/m(2) were recommended for the phase II study. All 47 patients were evaluable for toxicity and treatment response. The overall response rate was 55.3% (95% CI, 40.6-70.1%) and median duration of response was 4.2 months (range 0.9-9.5 months). After a median follow-up duration of 13.3 months, median overall survival was 12.7 months (95% CI: 10.4-14.9). The median time to progression was 5.0 months (95% CI, 3.4-6.5 months). The main toxicities (grade 3 or 4) were febrile neutropenia (14.9%), neutropenia (23.4%), diarrhea (10.6%) and neurotoxicity (8.5%). The combination of docetaxel and oxaliplatin was feasible with favorable toxicity profile and showed a promising anti-tumor activity in unresectable, metastatic gastric cancer patients.