The appearance of a second cancer in patients who had undergone curative operation for the first gastric cancer is one of the crucial problems for the clinician. We analysed data on 910 patients with gastric cancer treated with curative resection, with respect to the risk factors for second primary cancer and the prognosis. Of 910 patients, 69 (7.6%) died with a second primary cancer. In patients with a second primary cancer, there were more men and age was more advanced, compared to the survivors. The gastric tumor was larger, the serosal invasion was more prominent and lymphatic involvement was more frequent. The postoperative 5-year survival for patients with a second primary cancer was 60.9%, the 10-year rate was 31.9% and the 15-year was 19.6%. Multivariate analysis revealed that risk factors for a second primary cancer was advanced age, male sex and a larger tumor. Our findings suggest that during the follow-up of patients with gastric cancer treated by curative resection and risk factors, a second primary cancer may occur in other organs, in addition to a recurrence of the first cancer.