We report herein the rare case of a patient who survived for 5 years and 10 months after commencing treatment for gastric cancer with simultaneous disseminated peritoneal metastasis. A 45-year-old man was diagnosed as having advanced gastric cancer following the discovery of numerous nodules in the peritoneal cavity at laparotomy. The patient was treated by palliative gastrectomy and continuous hyperthermic peritoneal perfusion (CHPP) immediately after surgery on November 11, 1987. Postoperatively, he underwent radiofrequency (RF) hyperthermia with intraperitoneal cisplatin a total of seven times. He continued on a combination of uracil and tegafur (UFT) administered orally with a protein-bound beta-D-glucan extracted from the mycelia of Cariolus versicolor (PSK). Long-term survival was achieved following the initial palliative gastrectomy despite simultaneous disseminated peritoneal metastasis.