337 newborn, in whom a cardiovascular malformation was diagnosed at birth by criteria previously reported, were followed for variable period of time from January 1975 to December 1980. They came from a population of 32,561 live births which occurred at the Maternity of Florence in the same period. The diagnosis was confirmed by angiography, surgical procedure or autopsy in the 15 per cent of the whole group. Fifty-nine babies (18 per cent) with one exception died within the first year of age. Signs and symptoms referable to the cardiovascular malformation at birth disappeared during the follow-up period in 33.8 per cent of cases. Total incidence lowered from 10.3 per thousand at birth to 6.8 at the end of the follow-up. The percentage of normalized babies correspond to the frequency with which ventricular septal defects close spontaneously in the first period of age and accounts for the disappearance of this malformation from the first place of relative incidence of cardiac malformations in adults.