This is a retrospective study of 16 children with congenital complete atrioventricular block (CAVB) who were fitted with a pacemaker in infancy. All were neonates admitted at the age of 1 to 9 days for bradycardia; 3 had a cardiopathy. In 8 children a permanent pacemaker was implanted in the first two days of life on account of a heart rate slower than 50 beats/min, accompanied with threatening symptoms (heart failure or syncopes) in 4 cases. In 6 children the pacemaker was implanted at the age of 2 to 3 months; in spite of reassuring electrocardiograms, 5 of them were readmitted in an emergency for heart failure or syncope with slow heart rate; the 6th patient had disorders of ventricular excitability. Finally, 2 asymptomatic infants underwent pacing: one at 20 days for bundle branch block, the other at 6 months for slow phase abnormalities. Pacing was epicardial in all patients, the chamber being positioned in the space that separates the kidney from the parietal peritoneum. Ventricular synchronous pacing (VVI) was applied in 14 cases and atrioventricular pacing (DDD) in the two most recent cases. Two children died post-operatively, due to inadequate attachment of the electrode resulting in loss of ventricular capture in one case, and to extensive left atrial thrombosis in the other case. Two children died at a later stage of severe respiratory pathology. The 12 survivors were followed up for a mean period of 3.7 +/- 3.1 years. Three pacemakers were replaced: one at 28 months for infection, the others at 3 and 6 years respectively for running down of the batteries.2 +