Interruption of the aortic arch is an uncommon malformation in which there is no direct continuity between the aortic arch and the descending aorta, the latter arising through a patent ductus arteriosus. Three types are described, depending upon the site of interruption in relation to the arch vessels. A large ventricular septal defect is present in 94% of cases. It is to be distinguished from aortic arch atresia, which should be regarded as a severe form of preductal coarctation in which the luminal continuity of the arch and descending aorta is absent. Three cases are described: the first demonstrates the natural outcome of the uncorrected anomaly with progression to Eisenmenger's syndrome; the second illustrates the feasibility of surgical treatment in the neonate; the third is an example of total correction of aortic arch interruption with the common associated anomalies. Diagnosis in infancy is difficult in view of the paucity of definite clinical criteria. Surgery in the infant should consist of reconstruction of the aortic arch together with pulmonary artery banding. In older children total correction can usually be performed electively in a two-stage procedure.