In a recent editorial the statement was made that in 10 per cent of cases a diagnosis of cancer of the stomach is made when no cancer exists, or the diagnosis is missed when cancer is actually present, and that this faulty diagnosis is made by the roentgenologist, by the surgeon after the abdomen is opened, and even by the pathologist examining the specimen under the microscope. The purpose of this paper is to study the course of the disease in this group of cases and, if possible, to determine why mistakes are made, and how they can be avoided. The cases reported below should throw some light on this problem. Fifty per cent of all gastric cancers occur in the pyloric end of the stomach, 30 per cent occur in the pars media, and 20 per cent in the cardiac end. It is in this last group that the greatest number of mistakes are made so far as the roentgenologist is concerned. It is an interesting observation that whereas surgery in the cardiac end of the stomach is almost impossible, practically all examples of gastric cancer which are benefited by roentgen therapy occur here. Case I (Mrs. Y.): In this case the roentgenogram showed the filling defect typical of cancer of the cardiac end of the stomach (Fig. 1). A year earlier the patient had an x-ray examination which was negative (Fig. 2) in spite of the fact that symptoms had then been present for one year. Was there a cancer which could not be shown by x-ray at that time or did the cancer develop in the interval? While it is true that about 38 per cent of cases give a history of gastric symptoms for years, nevertheless, a careful study will reveal a change in the nature of these symptoms which marks the onset of malignancy. In Case I, even though the x-ray failed to show malignancy at the earlier examination, this must have existed, since the symptoms were always of the same type, with accompanying signs of anemia, loss of weight, and gross blood in the stomach contents. Probably a variation of x-ray technic to include a rugae examination would be helpful in cases of this kind. Even if this were negative, a laparotomy should be done in the presence of the symptoms observed. Case II (Mrs. P.): Fig. 3 shows another roentgenogram of the cardiac end of the stomach. For two years this patient had slight indigestion, gross blood in the stomach, loss of weight, and anemia. X-ray examinations by different roentgenologists were repeatedly negative, as this figure indicates. Laparotomy revealed cancer of the cardiac portion of the stomach. Case III (Mr. M.): This patient had had symptoms since December 1932. Fig. 4 shows the x-ray film taken several months after the onset of symptoms, which was reported negative. A filling defect is seen near the cardiac end.