OBJECTIVE: The objective of this study was to determine whether Apgar scores at 10 minutes are associated with death or disability in early childhood after perinatal hypoxic-ischemic encephalopathy. METHODS: This was a secondary analysis of infants who were enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network hypothermia trial. Infants who were born at ≥36 weeks' gestation and had clinical and/or biochemical abnormalities at birth and encephalopathy at <6 hours were studied. Logistic regression and classification and regression-tree analysis were used to determine associations between Apgar scores at 10 minutes and neurodevelopmental outcome, adjusting for covariates. Death or disability (moderate or severe) at 18 to 22 months of age was the measured outcome. RESULTS: Twenty of 208 infants were excluded (missing data). More than 90% of the infants had Apgar scores of 0 to 2 at 1 minute, and Apgar scores at 5 and 10 minutes shifted to progressively higher values; at 10 minutes, 27% of infants had Apgar scores of 0 to 2. After adjustment, each point decrease in Apgar score at 10 minutes was associated with a 45% increase in the odds of death or disability. Death or disability occurred in 76%, 82%, and 80% of infants with 10-minute Apgar scores of 0, 1, and 2, respectively. Classification and regression-tree analysis indicated that Apgar scores at 10 minutes were discriminators of outcome. CONCLUSIONS: Apgar scores at 10 minutes provide useful prognostic data before other evaluations are available for infants with hypoxic-ischemic encephalopathy. Death or moderate/severe disability is common but not uniform with Apgar scores of <3; caution is needed before adopting a specific time interval to guide duration of resuscitation. Copyright © 2009 by the American Academy of Pediatrics.