In order to achieve more correct diagnosis of gastriclesion, further progress in the technique of diagnosis is much desired. And so, in pursuing the more ideal study, about 7500 cases of U.G.I. studies taken in Severance Hospital in the past 29 months from May 1969 to September 1971, have been reviewed to evaluate how the following factors will affect the demonstrability of gastric lesion in upper G.I. series. 1. Introduction of air into the stomach by nasogastric tube. 2. Kinds and concentration of barium. 3. Demonstrability according to the position of the patient. 4. Use of antispasmodics.