There have been many reports on primary multiple cancer since Billroth reported it for the first time in 1889. Etiology ts not known, byt there are manu redisposing factors and developmental theories. The occurance of multiple primary malignant tumors is not just by coincidence, but significantly gigher in persons with a known cancer or with a history of cancer, than in the generel population. We report a case of double primary malignant tumors of esphageal squamous cell carcinoma and gastric adenocarinoma. The lesions were found during the gastrofiberscopic wxamination for the evaluation of dysphagia and epigastric pain. To descover occult malignancies, we emphasize the importance of special aggresive and diligent follow up of patients who are being treated for a known tumor. (Korean J Gastroenterol 1997; 29 : 411 -416)