PURPOSE: With recent advances in diagnostic techniques, and the increase in early cancers, the number of multiple primary cancers appears to be increasing. The recurrence of gastric cancer, after a radical operation, is the main cause of death, but the interest in the development of multiple cancers is also increasing. The purpose of this study was to evaluate the characteristics of gastric cancer with those of other combined organ cancers. METHODS: A comparison of 66 patients with multiple organ cancers, combined with gastric cancer, was made with 2, 444 of gastric cancer patients, who underwent operation at the Department of Surgery, Chonnam National University Hospital, between Jan. 1982 and Dec. 2000. RESULTS: The incidence of multiple cancers was 2.6% of the total gastric cancer patients. Of these 25.8% were detected at the same time as the gastric cancer, and 74.5% were detected before, or after, the operation for the gastric cancer. The sex ratio was 2: 1 with gastric cancer only, and 1.4: 1 with the multiple organ cancers, with a male predominance. The mean age of the multiple organ cancer patients was 57.1 years old (male: 59.4 years, female: 54.1 years), which showed no statistical difference to single gastric cancer. The location of the multiple cancers was common in the digestive tract, especially the colon. In terms of the histological types of gastric cancer, the incidence was highest in the poorly- differentiated, followed by the moderate and the well- differentiated cancers, respectively. However, the incidence of the poorly-differentiated type, in the multiple organ cancers, was lower than that in the single gastric cancer patients. There was no difference in stage between the multiple organ and gastric cancers. The 5-year survival rates were 51.6 and 50.6% in the gastric and multiple organ cancers, respectively, but with no statistical difference. The prognosis of multiple cancers wsa no different to that of single gastric cancer. CONCLUSION: This study suggests that more active treatment is needed in the treatment of gastric cancer, irrespective of involvement with other organ cancers.