We examined the significance of low-dose cisplatinum (CDDP) intraperitoneal administration for cases of peritoneal dissemination of gastric cancer. Sixty-eight cases of gastric cancer, diagnosed as P1 or CY1 in the gastrectomy operation that was carried out during the period between January 1994 and December 2001, were studied based on accumulated survival rate and mean survival time (MST). Ten milligram of CDDP was weekly administrated intraperitoneally through an infusion port. A two-week interval was taken after the eight-week administration. This group, the CDDP intraperitoneal administration group, was statistically superior both in the accumulated survival rate and MST. These results suggested that the low-dose CDDP intraperitoneal administration would contribute to improved prognosis of such gastric cancers as P1 or CY1.