To examine further the differences in birth-weight-specific neonatal mortality rates between ethnic groups, we studied causes of death for infants of white, black, United States-born Hispanic, and Mexican-born Hispanic women using linked California birth-death records from 1981 to 1983. Black infants of low birth weight had considerably lower neonatal mortality rates from respiratory distress syndrome and congenital abnormalities. In the normal birth-weight category, however, black neonatal mortality rates for most conditions were higher than those for whites. The greatest differences between Mexican-born Hispanic and white neonatal mortality rates were seen for other respiratory conditions and trauma/hypoxia/asphyxia. These differences were most marked in the 1500- to 2499-g and greater than or equal to 2500-g birth-weight categories. Attempts to lower the neonatal mortality rate for black infants of normal birth weight may require providers to focus on both broad preventive measures and improved perinatal management. In contrast, improvements in perinatal management among Mexican-born Hispanics may produce improvement in the neonatal mortality rate for this group.