All deceased infants were autopsied in a territory with a population of 1 220 000 inhabitants and a mean of 17 410 live births a year. During a period of 25 years (which preceded the introduction of advanced neonatal cardiac surgery), 393 neonates (6% of all deceased neonates) had died in whom a congenital heart malformation was found at autopsy. 118 (30%) of deaths were due to noncardiac causes. Lethal congenital noncardiac malformations caused death in 38 (10%) neonates. A perinatal disease (including birth trauma) was the cause in 65 (16%) neonates. An association of a noncardiac congenital malformation with a perinatal disease was involved in 6 (2%) neonates and a birth weight lower than 1000 g (together with a lethal perinatal disease or alone) was considered responsible in 9 (2%) neonates. Noncardiac but not unambiguously lethal malformations (mostly multiple) could at least have contributed to the fatal outcome in a further 86 (22%) neonates. A low birth weight could have contributed to death in 102 (26%) neonates, particularly in 42 (11%) neonates with a low birth weight associated with multiple noncardiac nonlethal malformations. A most probable or possible noncardiac cause of death was found in all cases of atrial septal defect, in 93% of tetralogies of Fallot, in 84% of ventricular septal defects, in 72% of hearts with double outlet right ventricle and in 57% of those with aortic coarctation. A congenital heart malformation was considered responsible for a fatal outcome in 82% of cases with discordant ventriculoarterial connexions ("transposition of the great arteries"), 79% of hypoplastic left hearts, 68% of pulmonary atresias and 53% of tricuspid atresias. The high proportion of noncardiac death noted to occur in the first postnatal day was found rapidly to decrease in the following days.