Between April 1974 and December 1987, 20 infants (six under one month of age) (mean weight 4.9 kg) underwent surgical valvotomy for critical aortic stenosis. Three of the four patients treated before 1976 died. Since 1979, 16 infants (four neonates) have undergone valvotomy with no deaths. Mortality for the whole group was 15%; in the neonates it was 33%. There were no late deaths. The survivors were followed up for a mean of 3 years 9 months and two required re-operations. The considerable improvement in surgical results in the past decade should be taken into account when newer techniques such as balloon dilatation are evaluated.