A combination chemotherapy with intra-peritoneal infusion of CDDP and continuous intravenous infusion of 5-FU was used with a total of 16 gastric cancer patients with peritoneal metastasis (P 2 or P 3). Infuse A-port was inserted at the time of operation, CDDP 70 mg/m2 was administered intra-peritoneally at day 1, and 5-FU 700 mg/m2 was continuously administered intravenously at day 1-5. This treatment was repeated twice. Toxicity was evaluated according to the criteria from JCOG. Major toxicities of this regimen were anemia, leukocytopenia and nausea/vomiting. Except for one patient with Grade 3 venous thrombosis, all toxicities were less than Grade 2 and well tolerable. Median survival time was 343 days, but, one patient has survived more than 6 years. According to the multivariate analyses, depth of invasion was selected as an independent prognostic factor for this treatment. This therapy is considered to be a safe and effective treatment modality for gastric cancer patients with peritoneal metastasis.