In a cohort of 1338 very preterm and/or very-low-birthweight infants, representing 94% of all infants born alive after less than 32 weeks' gestation or weighing less than 1500 g in the Netherlands in 1983, the neonatal mortality rate was 233 per 1000. In these infants, the best obstetric estimate of gestational age was a better predictor of neonatal mortality than birthweight. In such pregnancies, careful obstetric assessment of gestational age seems to be a more accurate basis for clinical decisions and management than the expected birthweight.