Congenital right diaphragmatic hernia is a potentially lethal defect if not properly diagnosed and repaired. Even when it is suspected clinically, recognition may be difficult as initial plain roentgenograms will perhaps appear normal. This report of four cases of herniation of the liver through the right diaphragm stresses the importance of serial roentgenograms and sometimes opaque studies in the diagnosis of this serious congenital defect. Incidence The rarity of congenital right-sided diaphragmatic hernia has been pointed out by several authors. Eppinger (1) presented 635 cases of herniation of the diaphragm; of these only 30 were congenital and on the right side. Kerr and Steinberg (2) reported 13 cases of diaphragmatic hernia with only 3 congenital through the right diaphragm. Case Reports Case I: McK., a male infant, was born prematurely Oct. 3, 1955, after thirty-two weeks of gestation. Birth weight was 4 1b. 1 oz. His condition was good at birth, but a few hours later there was a period of apnea and cyanosis and a few crackling râles were noted in both lungs posteriorly. Recovery was rapid, and the patient was in good condition on the following day, remaining so until the age of approximately one month. On Nov. 1, he became dusky, with cyanosis of the lips and finger tips, and vomited. The abdomen was distended. An abdominal scout film which was obtained the same day included the chest and revealed a normal heart and lungs, but more than the usual amount of air throughout the intestinal tract (Fig. 1). The liver was in a normal position under the diaphragm. Because of continued vomiting and distention, an exploratory laparotomy was performed Nov. 3. A rent of the serosa of the sigmoid colon with some turbid fluid in the abdomen was found. The postoperative course was uneventful until Nov. 15, when coarse râles again developed in both lung fields. Chest films disclosed a massive density in the right lung field area, thought to be fluid (Fig. 2). On Nov. 19, slight diaphragmatic tugging and some intercostal retraction were noted. The diminished breath sounds were considered to be caused by atelectasis. From Nov. 20 to Dec. 3, chest findings were variable: at times decreased breath sounds and dullness to percussion were present, while at other times the chest was clear. Finally, on Dec. 6 an attempt at thoracentesis was made, but no fluid was obtainable. The chest examination remained the same with decreased breath sounds, râles, and flatness to percussion on the right from Dec. 7 to 12, when severe respiratory distress developed. The child became cyanotic and died. An autopsy revealed absence of the right hemidiaphragm with herniation of the liver into the right hemithorax. Case II: MacF., a male infant, was born by normal spontaneous delivery on July 3, 1956, with a birth weight of 5 1b. 14 oz. Slight transient cyanosis responded to oxygen therapy.