OBJECTIVES To determine neonatal global and regional brain volumes in infants with congenital heart disease (CHD) in comparison with healthy controls and to determine brain growth. STUDY DESIGN Prospective cohort study in infants undergoing open-heart surgery for complex CHD. Global and regional volumetric measurements on preoperative cerebral magnetic resonance imaging were manually segmented in children without overt brain lesions. RESULTS Preoperative brain volumetry of 19 patients demonstrates reduction in total and regional brain volumes, without any specific regional predilection compared with 19 healthy control infants (total brain volume reduction: 21%, regional brain volume reduction 8%-28%, all P < .001). CONCLUSIONS Infants with CHD undergoing bypass surgery have smaller brain volumes prior to surgery without a specific regional predilection. This suggests a fetal origin of reduced brain growth.