The radiologic study of the pancreas oriented in the upper retroperitoneal space is difficult because the specific density of this viscus is the same as that of its surrounding tissue, so that it cannot be visualized directly. Furthermore, it is one of the few viscera in the abdomen which cannot be outlined by a contrast medium. In the acute abdomen, the diagnosis of acute pancreatitis is very important since the present treatment of this disease is conservative, which emergency laparatomy is indicated in most other abdominal crises. However, the diagnosis of acute pancreatitis cannot be made by roentgen studies alone, yet such studies can at times confirm an uncertain clinical diagnosis when evaluated with clinical findings and can occasionally alert the unsuspecting clinician to the possible presence of this disease. Because a radioligic examination plays such an important role in the differential diagnosis of the acute abdomen and at present augmenting interest for pancreat c diseases, we present this discussion in order to focus attention on the radiologic features of acute pancreatitis. 1. From Nov. 1968 to June 1978, roentgenologic studies of 275 patients diagnosed as acute pancreatitis were reviewed. 2. In this series, the important findings on the chest roentgenograms of 275 cases were as follows. 1) Fifty-five cases (20.0%) of these represented pleural effusion. 2) Platelike atelectasis at the lung bases was noted in 44 cases (16.0%). 3) There was elevation of the diaphragm in 33 cases (12.0%). 3. The significant findings on the simple abdomen of 247 cases were as follows. 1) The presence of a“sentinel loop”occured in 168 cases (68.0%). 2) Colon“cut-off”sign was noted in 106 cases (42.9%). 3) Obliteration of psoas shadows in 8 cases (3.2%). 4) Gastrocolic separation in 4 cases (1.6%). 4. One hundred and seventy-five barium meal studies of the stomach and duodenum were available for review. 1) Irritability of the duodenal bulb in 22 cases (11.3 ). 2) Pressure indentation on the antrum of stomach and duodenum in 18 cases (9.2%). 3) Enlargement of the duodenal sweep of 17 cases (8.7%), and 4) Increased retrogastic space and serration on the duodenal loop were noted respectively in 8 cases (4.1%). 5. Oral cholecystograms in 127 cases and I.V. cholangiograms in 86 cases were performed. 1) Nonvisualization of gallbladder in 19 cases (15.0%) of oral and 18 cases (20.9%) of I.V. 2) Gallstones of 12 cases, and 3) Common bile duct stones in 4 cases were noted. 6. It is considered that the diagnostic accuracy of acute pancreatitis may be increased only by simple chest, abdomen and U.G.I. series if careful attention should be given on examination.