Peritoneal dissemination is a major event in the development of gastric cancer. However, most patients with it have been excluded from clinical studies because they rarely have measurable lesions. We conducted an analysis to evaluate the efficacy and feasibility of modified pharmacokinetic modulating chemotherapy, for gastric cancer patients with peritoneal dissemination. Between May 2002 and April 2004, 10 patients were treated by modified pharmacokinetic modulating chemotherapy. This analysis was based on 10 consecutive chemotherapy-naive patients with confirmed peritoneal dissemination. This therapy regimen was repeated with a weekly schedule of MTX 100 mg/body, given as intraarterial infusion 1 h prior to a 24-hr infusion of 5-FU 500 mg/body. Simultaneously, enteric-coated tegafur/uracil (400 mg) was administered every day. The one-year overall survival rate was 50. 0%. The median survival time was 311 days. Grade 1 stomatitis and Grade 1/2 oral dryness were involved in 40% of the cases. No patient had to discontinue this therapy because of complications. Objective improvement of ascites was seen in all patients, and all patients could be treated at outpatient clinics. This regimen may be well-tolerated and of clinical benefit for patients with peritoneal dissemination of gastric cancer.