To determine the prognostic import of neonatal seizures according to the presence or absence of certain other postnatal characteristics, we studied a population of 39,000 infants with birth weight greater than 2500 gm. Children with clinically recognized neonatal seizures and 5-minute Apgar scores less than or equal to 5 and who had at least one of five signs compatible with neonatal encephalopathy had a risk for first-year death of 33%. Survivors of this cluster of events (low Apgar score-abnormal signs-seizures) had a risk for motor disability of 55%. In contrast, survivors of neonatal seizures who did not have poor Apgar scores or other abnormal signs had a risk for motor disability of only 0.13%. Thus, among infants with neonatal seizures the risk for cerebral palsy was 420 times greater if there had been a low 5-minute Apgar score and other neonatal signs. Low Apgar score-abnormal signs-seizures constituted a cluster of events that served to identify, within the first days of life, a tiny subgroup of term newborn infants in whom risk for chronic motor disability was 55%, and for death or disability was 70%.