Controversy exists regarding the integrity of the nervous system in the newborn with a congenital heart defect who must undergo corrective or palliative open heart surgery. Neurodevelopmental sequelae have been primarily attributed to surgical procedures without standardized evaluation of the preoperative neurologic status. OBJECTIVE To determine whether newborns with congenital heart defects demonstrate abnormalities in neurobehavioral status before surgery. METHODS In this prospective study, a standardized neonatal neurobehavioral assessment and a neurologic examination were conducted independently in a consecutive series of 56 neonates referred to our hospital for investigation of open heart surgery. RESULTS Neurobehavioral and neurologic abnormalities were documented in greater than half of the cohort and included hypotonia, hypertonia, jitteriness, motor asymmetries, and absent suck. Poor state regulation (62%) and feeding difficulties (34%) also were commonly observed. Furthermore, 3 subjects had seizures, 35.7% were microcephalic, and 12.5% were macrocephalic. The overall likelihood of neurobehavioral abnormalities was not enhanced by indicators of cardiorespiratory compromise. Interestingly, newborns with acyanotic congenital heart defects were more likely to demonstrate neurologic compromise than were those with cyanotic defects. CONCLUSIONS Findings suggest that the prevalence of neurobehavioral abnormalities before surgery in newborns with congenital heart defects has been underappreciated and would indicate that factors other than intraoperative procedures should be considered in the genesis of brain injury in this population.congenital heart defects, neurologic examination, newborn.