Treatment for peritonitis carcinomatosa in gastrointestinal cancer remains to be established though it is one of the commonest causes of cancer death. Subtotal peritonectomy (SP) with chemohyperthermic peritoneal perfusion (CHPP) was developed for the new therapeutic strategy for peritoneal dissemination in gastrointestinal cancer in our department. SP includes resection of stomach, colon, small bowel, spleen, gall bladder, and parietal peritoneum. CHPP was carried out by heated saline containing 25 mg/l cisplatin, 10 mg/l mitomycin C, and 20 mg/l etoposide. Intraperitoneal temperature was maintained at 42 degrees C for 60 min. Fifteen gastric cancer and three colon cancer patients with severe peritoneal dissemination underwent these procedures. The averages of operating time, intraoperative bleeding volume, and total perioperative transfused blood volume were 9 h, 4400 ml, and 5600 ml, respectively. The patients estimated as complete resection and residual disease by histopathological study numbered 11 and 7. There was no treatment-related deaths though bleeding occurred in 5 patients; perforation in 2 patients; and abscesses in 2 patients. The 1-year survival rate (1ysr) and the 2-year survival rate (2-ysr) of all the patients were 57% and 21%, respectively. The 1-ysr and the 2-ysr of the patients who underwent complete resection were 67% and 40% significantly greater than the 43% and 0% of the patients who had residual tumors (p=0.02). The combination therapy of SP and CHPP is feasible in spite of its morbidity and has great possibilities in complete resection of peritoneal dissemination and prolongation of patient's survival.