Congenital heart defects are diagnosed in approximately 1% of births in the United States and account for the largest proportion of infant mortality attributable to birth defects. Congenital heart defects are multifactorial in origin and have several recognized genetic causes (e.g., DiGeorge and Williams-Beuren syndromes) and noninherited risk factors (e.g., maternal pregestational diabetes and rubella infection). Approximately 70% of infant deaths attributable to congenital heart defects occur neonatally (age <28 days). U.S. studies have shown that all-cause neonatal mortality rates are higher among term infants of black mothers compared with white mothers, but lower among preterm infants of black mothers compared with white mothers. To assess neonatal mortality attributable to congenital heart defects by maternal race and gestational age, CDC analyzed linked U.S. birth and infant death data for 2003--2006. This report summarizes the results of that analysis, which found that 4.2% of all neonatal deaths and 24.5% of neonatal deaths attributable to birth defects had a congenital heart defect noted as the underlying cause. Among preterm births (<37 completed weeks' gestation), neonatal mortality rates attributable to congenital heart defects were lower for blacks (4.5 per 10,000 live births) compared with whites (6.8). However, among term births (≥37 completed weeks' gestation), neonatal mortality rates attributable to congenital heart defects were higher for blacks (1.5 per 10,000 live births) than for whites (1.3). The reasons for these racial differences by gestational age are unclear and will require further examination, including assessment of differences in prenatal diagnosis and prevalence at birth of congenital heart defects, and reporting of causes of death.