Background: The 10-point Apgar score has been used to assess the condition and prognosis of newborn infants throughout the world for almost 50 years. Some investigators have proposed that measurement of pH in umbilical-artery blood is a more objective method of assessing newborn infants. Methods: We carried out a retrospective cohort analysis of 151,891 live-born singleton infants without malformations who were delivered at 26 weeks of gestation or later at an inner-city public hospital between January 1988 and December 1998. Paired Apgar scores and umbilical-artery blood pH values were determined for 145,627 infants to assess which test best predicted neonatal death during the first 28 days after birth. Results: For 13,399 infants born before term (at 26 to 36 weeks of gestation), the neonatal mortality rate was 315 per 1000 for infants with five-minute Apgar scores of 0 to 3, as compared with 5 per 1000 for infants with five-minute Apgar scores of 7 to 10. For 132,228 infants born at term (37 weeks of gestation or later), the mortality rate was 244 per 1000 for infants with five-minute Apgar scores of 0 to 3, as compared with 0.2 per 1000 for infants with five-minute Apgar scores of 7 to 10. The risk of neonatal death in term infants with five-minute Apgar scores of 0 to 3 (relative risk, 1460; 95 percent confidence interval, 835 to 2555) was eight times the risk in term infants with umbilical-artery blood pH values of 7.0 or less (relative risk, 180; 95 percent confidence interval, 97 to 334). Conclusions: The Apgar scoring system remains as relevant for the prediction of neonatal survival today as it was almost 50 years ago. Copyright © 2001 Massachusetts Medical Society.