The clinical features, investigation, treatment and outcome of four newly born babies with the following recognisable triad of findings are presented: Bilateral pulmonary compression with or without hypoplasia. Massive pericardial effusion without cardiac compromise. An intrapericardial hernia containing part of the liver. The primary event in the causation of this triad is a congenital defect in the central tendon of the diaphragm. Compromised hepatic venous outflow involving the herniated part of the liver is the postulated origin of the fluid within the pericardium (Budd-Chiari-like effect). Although rare, this triad is clinically identifiable. Sonar imaging clinches the diagnosis. Surgical correction is simple but the prognosis depends on the presence of pulmonary hypoplasia which caused death in two cases and on other described lethal associated anomalies which were not encountered in the reported patients.