In an attempt to prevent postoperative intraperitoneal recurrence in patients with advanced gastric cancer and consequently to improve survival time, we treated patients with intraperitoneal hyperthermic perfusion (IPHP) using mitomycin C (MMC) combined with surgery. There were 60 patients with advanced gastric cancer who were treated with IPHP (long-term study) group, and the survival of this group was compared with the outcome in 52 patients with advanced gastric cancer treated with surgery alone (control group). To avoid or diminish side effects derived from scald injury of the peritoneal surface due to IPHP, 50 mg/kg of cimetidine was given intravenously just before administration of IPHP. For prophylaxis of anastomotic leakage, duodenostomy using a Foley catheter was performed. The 60 patients who were treated with IPHP lived longer than the 52 patients in the control group (p = 0.000610). The 3 year survival rate was 45 percent for the former compared with 16 percent for the latter. The intravenous administration of cimetidine just prior to IPHP protected the peritoneoserosal surface from scald injury, even though the heated perfusate exposure was at 44.3-46.3 degrees C for 2 hours. Because the intraabdominal pressure within the duodenum and jejunum was decompressed postoperatively through catheter duodenostomy and the peritoneoserosal surface was protected from scald injury caused by IPHP, anastomotic leakage in the study group was nil. Therefore, IPHP treatment plus aggressive surgery combined with pre-IPHP cimetidine administration are indicated for patients with advanced gastric cancer. The side effects of IPHP and postoperative morbidity can thus be reduced and a favorable outcome obtained.