Right diaphragmatic hernia in the newborn. It is uncommon for herniation of the liver through a right diaphragmatic defect to present in the neonatal period. Four infants are described who developed respiratory distress within four hours of birth and were thought to have a Group B beta haemolytic streptococcal infection. In all four the diaphragm seemed normal on the first X‐rays. Progressive herniation of the liver, which occurred during the first week after birth, initially resulted in confusing clinical and radiological findings which were ascribed to worsening pneumonia and pleural effusion. The importance of serial X‐rays of the chest and abdomen and the presence of loops of gas‐containing bowel in the right upper quadrant of the abdomen, as indicators of right diaphragmatic herniation, are emphasized. Two diagnostic techniques are described: in two infants, a right pneumothorax after oxygen‐induced pneumoperitoneum confirmed a communication between the peritoneal and right pleural cavities; in the other two infants, comparison of X‐rays taken during spontaneous breathing and forced inspiration revealed in the latter substantial clearing of the right lung field and descent of the liv