To establish the diagnostic criteria on X-ray findings for the stomach mass examination survey film, comparative study on the X-ray findings of the mass examination survey films with the findings of the resected stomach had been done. For this purpose, I have studied 74 lesions in 47 cases. The results were as follows: 1) About 80% of them were demonstrated as the filling defect. The relations among the demonstration of the filling defect and the size of the lesion, and pathohistologic findings were as follows: Ⅰ) The lesions measuring over 4 cm in diameter were demonstrated as the irregular filling defect. Ⅱ) The lesions with the size of 2 to 4 cm in diameter were demonstrated halves as the irregular filling defect and halves as a faint filling defect. Ⅲ) The lesions measuring within 2 cm in diameter were demonstrated as the faint filling defect. Ⅳ) As to the pathohistologic findings, many of the advanced cancer were demonstrated as the irregular filling defect but early stomach cancer and the benign lesions had no such plain findings. 2) The small lesions not demonstrated as the filling defect were demonstrated as a irregular margin, abnormal relief view. etc. These X-ray diagnosis were needed in order to detect the small protruding lesions. 3) The Barium filled stomach in prone position was most important and upright position was also important.