PURPOSE: To determine whether an early magnetic resonance imaging (MRI) study using perfusion-weighted imaging (PWI) may define the pattern of brain injury in term neonatal hypoxic-ischemic (HI) encephalopathy. MATERIALS AND METHODS: Five newborns with HI encephalopathy or a marker of perinatal depression, and 2 controls underwent an early MRI (at 2 to 4 days), including PWI. Relative cerebral blood flow (rCBF) values were measured. RESULTS: On early (<or=4 days) PWI-MRI, marked hyperperfusion was seen in areas of HI brain damage, allowing the classification of the children into different patterns according to the predominant site of injury: 1 with a "normal pattern"; 1 with a "watershed pattern" with increased rCBF ratios in white matter; 1 with a "basal ganglia pattern" with increased rCBF ratios in basal ganglia; and 2 with a "total cortical pattern" with increased rCBF ratios in cortical gray matter, white matter, and basal ganglia. These patterns were confirmed in all infants on late (9 to 11 days) conventional MRI (T2-weighted images) (4 of 5 patients) or on postmortem examination (1 of 5 patients). CONCLUSION: PWI is technically feasible in neonates with HI encephalopathy in a reproducible way, permitting comparisons between children. It provides a practical means to identify early after birth the future definitive ischemic areas that may be shown on conventional MRI only later.