Background: The aim of this clinical study was to evaluate the efficacy of combination chemotherapy of oxaliplatin, leucovorin and continuous-infusion 5-fluorouracil (5-FU) for advanced gastric cancer. Methods: Patients with previously untreated gastric cancer with measurable disease received oxaliplatin (100 mg/m2, day 1), followed by leucovorin (100 mg/m2, day 1) and 5-FU (2,400 mg/m2, days 1–2), which was repeated every 2 weeks. The primary endpoint was overall response rate (ORR) and secondary endpoints were progression-free survival (PFS), overall survival (OS) and toxicity. Results: Forty-eight patients were enrolled, and 45 were evaluable for response. A total of 320 cycles of chemotherapy were administered (median 6 cycles per patient). One complete response (2.1%) and 19 partial responses (39.6%) were noted, resulting in an ORR of 41.7% (95% confidence interval, CI: 27.7–55.6%) by intent-to-treat analysis. With a median follow-up duration of 22 months, the median PFS was 5.3 (95% CI: 2.8–7.8) months and the median OS was 13.6 (95% CI: 9.3–17.9) months. There was 1 treatment-related death, and the most common grade 3/4 toxicity was neutropenia (36.1%). Three patients discontinued treatment because of serum creatinine elevation. Conclusion: This study reaffirms the efficacy of oxaliplatin in advanced gastric cancer, but its dose of 100 mg/m2 remains to be reconsidered in Korean patients.