Purpose: Because of an improving gastric cancer detection program and treatment methods, we can expect improved survival of patients with gastric cancer. Given the longer survival times, the chance of an occurrence of multiple primary malignant tumors other than stomach is increased in the same patients. The purpose of this study is to analyze the clinical characteristrics and the survival of patients with gastric cancer and other malignancies. Materials and Methods: A retrospective study of 3669 patients with gastric cancer observed at our department between January 1994 to December 2002 was conducted. Associated tumors were diagnosed using the Warren and Gates criteria, and included tumors that were not considered to be a metastasis, invasion, or recurrence of the gastric cancer. Results: Of all 3669 patients, $2.07\%$ (n=76) had primary tumors other than gastric cancer, $63\%$ of which were synchronous (n=48) and $37\%$ metachronous (n=28). The mean age of the study group was 64.9 (65.5 in males, 61.8 in females), and the male-to-female ratio was 4.8 : 1. The most common cancer associated with gastric cancer was a hepatocellular carcinoma ($23.7\%$), followed by colorectal cancer ($17.1\%$), esophageal cancer ($10.5\%$), breast cancer ($6.6\%$). Of the 45 patients who had undergone a resection, 14 were in stage I, 12 in stage II, 13 in stage III, and 6 in stage IV. No statistically significant differences were found between the synchronous and the metachronous groups with regard to age, sex ratio, differentiation, and stage. The 5-year survival rates of the metachronous and the resected patients were significantly higher than those of the synchronous and the non resected patients, respectively. Conclusion: Due to increasing length of the follow-up period for patients with gastric cancer, another malignancy may develop in other organs. Therefore, physicians should pay attention to detect other cancers early in these patients, and a surgical resection is recommended as the treatment of choice in the management of multiple primary cancer associated with gastric cancer.