Cerebral blood flow (CBF) in newborn infants is often below levels necessary to sustain brain viability in adults. Controversy exists regarding the effects of such low CBF on subsequent neurologic function. We determined the current childhood neurologic status and IQ in 26 subjects who had measurements of CBF performed with PET in the neonatal period between 1983 and 1989 as part of a study of hypoxic-ischemic encephalopathy. Follow-up information at ages 4 to 12 years was obtained on all 26 subjects. Ten subjects had died. All 16 survivors underwent clinical neurologic evaluation, and 14 also underwent intelligence testing. Eight had abnormal clinical neurologic evaluations; eight were normal. The mean neonatal CBF in those with abnormal childhood neurologic outcome was significantly higher than in those with normal childhood neurologic outcome (35.64 ± 11.80 versus 18.26 ± 8.62 mL 100 g-1 min-1, t = 3.36, p = 0.005). A significant negative correlation between neonatal CBF and childhood IQ was demonstrated (Spearman rank correlation r = -0.675, p = 0.003). Higher CBF was associated with lower IQ. The higher CBF in subjects with worse neurologic and intellectual outcome may reflect greater loss of cerebrovascular autoregulation or other vascular regulatory mechanisms due to more severe brain damage.