As progressively larger percentage of long-term survivors are being reported, the proportion of patients with subsequent primary lesions are increasing. This study is the clinical analysis of 17 cases of multiple primary malignant tumors confirmed fillowing the pathologic diagnosis of gastric cancer at the Department of Surgery, Keimyung University School of Medicine during the past 10 years from 1984 through 1994. These deta show that, when cancer first appears at a specific anetomic site, certain organs are more susceptible to second primary lesions than other sites. The ratio between male and female was 2:1 and mean age of incidence was 60 years. The ratio between synchronous and metachronous lesions was 1:2. The average time interval between first and second cancer was 3.0 years in metachronous cases. After the diagnosis of stomach cancer, the most frequently involved second organ was colorectum, others were liver, cervix, thyroid, and neck in decreasing order. Pathologic stage, tumor differentiation, tumor size, lymph node metastasis of the first lesions were unrelated to subsequent malignant tumor after stomach cancer diagnosis.