We analyzed early and late results of surgical treatment of 100 consecutive children with Down's syndrome (DS) and congenital heart defect (CHD) who were operated on between 1990 and 1997. Fifty had common atrioventricular canal (CAVC), 24 ventricular septal defect, 8 the ostium primum atrial septal defect, 8 tetralogy of Fallot (TOF), 3 patent ductus arteriosus, 3 the ostium secundum atrial septal defect, and 4 CAVC coexisting with TOF. In 93 patients total correction was performed. The total death rate was 6%. Death in the CAVC group was 8%, but it decreased to 2.7% during the past 3 years. The children who were followed up (from 7 months to 6 years; mean, 39 months) are in NYHA class I or II. There were no reoperations. The postoperative course was complicated by pulmonary infections in 38% of patients, which converted to generalized infection in 10% and was the cause of death in 8% of patients. These results indicate that CHD in DS children can be repaired with a low death rate and low incidence of severe mitral atrioventricular valve regurgitation in the CAVC group. A high incidence of severe infections can influence the final results. Repair of CHD in infancy helps to eliminate problems connected with congestive heart failure and pulmonary hypertension.