Children with Down's syndrome and congenital heart defects have multiple problems. The role of cardiac surgery in the management of these patients was investigated by reviewing the clinical data, hospital course and follow-up of 21 patients (9 males and 12 females, age range 1 month to 14 years) with Down's syndrome and congenital heart defects operated in our institute. Twelve (57%) of these were infants and nine (43%), older children. Five were in congestive cardiac failure, four were hypothyroid. The heart lesions ranked in incidence as follows: atrioventricular septal defect 7 (33.3%), tetralogy of Fallot 3 (14.3%), tetralogy of Fallot & atrioventricular septal defect both 2 (9.5%), double outlet right ventricle with pulmonary stenosis 1 (4.8%), patent ductus arteriosus 2 (9.5%), patent ductus arteriosus plus coarctation 1 (4.8%), ventricular septal defect 2 (9.5%), atrial septal defect plus ventricular septal defect 1 (4.8%), atrial septal defect plus patent ductus arteriosus plus right pulmonary artery stenosis 1 (4.8%) and transposition of great arteries with multiple ventricular septal defect 1 (4.8%). Four (19%) patients had palliative procedures while the rest (81%) underwent primary repair. All survived the operation. The post-operative period was complicated in 6 (28.5%), with respiratory infections in 3, pulmonary hypertensive crisis in 2 and complete heart block in 1. The early mortality was 0, while there were 2 (9.5%) late deaths. The number of hospitalisations was markedly reduced according to the parents. Follow-up showed near normal pulmonary artery pressure in 50 percent children with large shunts and a good developmental spurt was seen in 60 percent. From a purely surgical viewpoint, the prognosis for children with Down's syndrome and congenital heart disease is good.