The addition of Futraful to MMC therapy of gastric carcinoma was evaluated. Nationwide 297 institutions participated in a randomized controlled study and cumulative five-year survival rate was calculated. A total of 1,673 cases was studied. These were divided in two groups: Group A, without Futraful, and Group B, with Futraful. Futraful was administered postoperatively for 3 months. The MMC treatment was done by moderate intermittent administration (Method I) or by large dose administration (Method II). Futraful improved survival rates regardless of the method of MMC treatment. Especially, Group B' (more than 60 g of Futraful) showed significantly better results in patients with metastases and positive serosal invasion in both methods, and beta type infiltration in Method I. Furthermore the Group B' patients had higher survival than Group A patients in Method II for patients in stage III and gamma type infiltration. Method II, a large dose MMC, plus Futraful was suggestive of particular effectiveness in preventing peritoneal metastases in curatively resected cases.