Heptaplatin is a new platinum derivative with antitumor activity against gastric cancer. Preclinical studies showed that it is less toxic than other platinum analogues. The purpose of this study is to evaluate the efficacy and toxicity of the combination therapy of heptaplatin and 5-fluorouracil in Korean advanced gastric cancer patients. This study was investigated retrospectively. The patients group consisted of 65 advanced gastric cancer patients with no prior radiotherapy. All patients received heptaplatin $400;mg/m^2$ by 2-3 hour infusion on Day 1 and 5-FU $1000;mg/m^2by 12-24 hour continuous infusion for 5 days. After the first cycle, subsequent doses were adjusted according to the toxicity. Courses were repeated every 28 days. As results, objective response occurred in 16 patients $(24.6\%)$. Two were complete and 14 were partial response. Median progression free survival was 32 weeks with $29\%$ of patients progression free at 1 year. The most common hematologic toxicity was anemia. Grade 3 or 4 anemia was seen at $2.7\%$ of treatment cycles. Grade 3 or higher leucopenia was seen at $1.2\%$ of cycles. Grade 3 or 4 neutropenia and thrombocytopenia occurred at $6.1\%;and;1.5\%$ of cycles, respectively. The most common nonhematologic toxicity was proteinuria. Though no patients experienced grade 3 or 4 proteinuria, proteinuria was a considerable factor for this chemotherapy. Grade 3 or higher gastrointestinal toxicities were nausea and vomiting ($4.6\%$ of patients) and diarrhea ($1.5\%$ of patients). Grade 2 renal toxicity with elevation of serum creatinine was seen in $0.3\%$ of cycles, which is less than that of other platinum analogues. This study showed that combination therapy of heptaplatin and 5-FU have modest antitumor activity against advanced gastric cancer without severe renal toxicity.