Congenital diaphragmatic eventration is a rare disease and generally accepted as an abnormally high position of part or all of the diaphragm, usually associated with a marked decrease in muscle fibers and a membranous appearance of the abnormal area. There were 4 cases of the congenital diaphragmatic eventration at the Dept. of Thoracic Surgery, Seoul National University Hospital, from 1957 to 1977. They were two boys and two girls and ranging from 1 day to 3 years of age. They were all repaired by surgical operation and one was expired postoperatively, another one was dead one year later due to complication. The ratio between right and left was 1:3 and their symptoms were cyanosis, dyspnea and frequent respiratory disease. In physical examination there was noted decreased breathing sound on the affected lung field and bowel sound was audible in some cases. Diagnosis was done by Chest X-ray and plication of the affected diaphragm was usually done in operation. There were noted atelectasis and cystic change of the affected side lung. And the liver, colon, spleen and small intestine were found in the dome of the eventrated diaphragm.[KTCS 1978;1:92-96]