The presence of Down syndrome can influence the timing of surgical correction of congenital heart defects due to the increased and early incidence of pulmonary hypertension. As part of a population-based outcomes study of congenital heart disease, we have formed a registry of all Oregon residents who have had surgery for one of 12 congenital heart defects at≤18 years of age from 1958 to the present (N=3,965). To determine morbidity and mortality, the cohort is contacted by questionnaire or phone interview every two years. Down syndrome was present in 4% of the cohort with tetralogy of Fallot, 13% of VSD, 3% of ASD, 3% of PDA, 27% with partial atrioventricular canal, and 76% with complete atrioventricular canal. No one who had surgery for aortic stenosis, coarctation of the aorta, pulmonic stenosis, or transposition of the great arteries had Down syndrome. Surgical correction tended to occur at significantly younger age with Down syndrome and VSD (Down 1.9±3.0 yrs vs Non-Down 3.5±3.5 yrs, p<0.001), ASD (Down 3.2±3.2 yrs vs Non-Down 6.5±4.4 yrs, p<0.001), partial atrioventricular canal (Down 3.9±3.9 yrs vs Non-Down 6.5±5.7 yrs, p<0.01), and complete atrioventricular canal (Down 0.7±1.3 yrs vs Non-Down 2.2±2.7 yrs, p<0.01). The presence of Down syndrome had no significant effect on survival after surgery for VSD, ASD, partial atrioventricular canal, and PDA. After surgery for tetralogy of Fallot, survival with Down syndrome was poorer (p=0.06): Down syndrome - 30-day survival 0.95±0.05, 10 yr survival 0.80±0.09; Non-Down - 30-day survival 0.89±0.02, 10 yr survival 0.86±0.02. Survival with Down syndrome was also less with surgery for complete atrioventricular canal(p=0.05): Down syndrome - 30-day survival 0.84±0.04, 5 yr survival 0.77±0.04, 10 yr survival 0.75±0.04 vs Non-Down - 30-day survival 0.94±0.04, 5 yr survival 0.90±0.05, 10 yr survival 0.90±0.05. Hence, despite earlier surgical intervention on average, survival tends to be poorer for children with Down syndrome and surgery for complete atrioventricular canal or tetralogy of Fallot, but not for VSD, ASD, partial atrioventricular canal, or PDA. Additional analyses will be necessary to separate any effects on survival of early age at surgery with Down syndrome in recent years.