In approximately 80% of patients with scirrhous carcinoma of the stomach, recurrence of cancers occurs even after potentially curative resection, and recurrence most frequently occurs in the form of peritoneal metastasis. Such recurrence may be attributable to possible intraperitoneal dissemination of malignant cells already present at the time of surgery. We performed intraoperative peritoneal cytology on patients with scirrhous carcinoma of the stomach. Free cancer cells were demonstrated in the Douglas cavity in 16 of 32 (50%) patients who underwent potentially curative gastrectomy. The postoperative 5-year survival rate was 23% in patients without detectable free cancer cells in the peritoneal cavity, compared with only 9% in patients with microscopic evidence of intraperitoneal free cancer cells. Therefore, we have applied hyperthermic continuous peritoneal perfusion (CHPP) on patients with scirrhous carcinoma of the stomach in order to develop a surgical adjuvant therapy effective for the prevention of recurrence of peritoneal involvement. The results obtained so far from our study have shown an increased 3-year survival rate of patients undergoing potentially curative gastrectomy, but no improvement of therapeutic outcome in terms of postoperative 5-year survival.