We describe the prevalence of extra-cardiac anomalies in children with congenital cardiac malformations, and their impact on survival, compared to the outcome in children with the congenital cardiac lesions as the only recognised anomaly. Our population comprises the 3527 children born with congenital cardiac anomalies between 1990 and 1999, and registered at the largest tertiary centre for Paediatric Cardiology in Norway. Extra-cardiac anomalies were found in one-fifth of the population, with Down's syndrome accounting for nearly one-third. Survival improved for children born between 1995 and 1999 compared with those born in the period from 1990 to 1994 for all groups, except for children with additional extra-cardiac anomalies in the absence of Down's syndrome. The results were the same for children undergoing surgical treatment of their cardiac malformation. The survival in children with Down's syndrome improved in comparable fashion to those without extra-cardiac anomalies. Children with extra-cardiac anomalies in the absence of Down's syndrome represent a heterogeneous group, with varying patterns of survival. Survival did not improve in these latter patients during the period of our study.