Introduction: Only few data are available in literature regarding the long term outcome of the newborns with isolated congenital complete heart block (CHB). The aim of the study was to describe neonatal morbidity, incidence of minor heart defects, mortality and the risks of poor outcome in the patients with CHB diagnosed in utero or as a newborn.Patients and methods: Since 1950, CHB whithout structural abnormality has been diagnosed in 152 children aged between 0-15 years in five tertiary centers in Finland. Diagnosis was made in utero or postnatally in 91 children with a median gestational age of 29.3 weeks. Maternal connective tissue disease was evident in 90% of the cases. At birth the median gestational age was 37.1 weeks (range 29–41) and the median birthweight 2969 g (range 905–4370 g). Sixty infants of 91 (66%) were girls and 7 of 91 (8%) were twins. Mean follow-up time was 10.6 years (range 0–47.5 years).Results: Fetal heart rate at diagnosis was 57 beats/min (median), and after birth 56 beats/min. Delivery route was cesarean section in 57% of cases. Insidence of neonatal morbidity was 58%; hydrops 27%, cardiac failure 46%, symptoms of neonatal lupus 18%, symptomatic PDA 16%, RDS 8%, NEC 7%, 1VH 6% and pulmonary hypertension 4%. There were 6 perinatal deaths (7%; one in utero and 5 postnatally). Pacing as a newborn was indicated in 48 of 90 cases (53%); 36 received pacemaker (PM) at older ages.