PIP: During the 2 1/2 decades between 1957 and 1982, neonatal mortality rates in Peninsular Malaysia declined by almost 60% from 29.6 to 12.1/1000 births, with a gain in the momentum during the most recent period. The proportionate contribution of neonatal deaths to infant deaths increased from about 39% in 1957 to some 63% in 1982, reversing its relative contribution with that of post-neonatal mortality. Even more striking is the fact that deaths during the 1st 7 days constituted some 82% of all neonatal deaths and 53.2% of infant deaths. This clearly indicates that decline in mortality during the early neonatal period has not been as rapid as during the postnatal period. The probability of surviving the 1st month of life remains much higher in districts where socioeconomic, health and environmental conditions are more favorable. Along with socioeconomic development, concerted efforts to provide basic water, sanitation and health services will narrow the existing gaps among the districts and bring about a further reduction in the overall neonatal mortality rate. Areal regression analyses indicate that mortality is influenced by a host of factors which are mutually reinforcing. Neonatal mortality rate tends to be higher in districts which are less urbanized and which have higher Malay concentration and in districts with poor socioeconomic and health conditions. High fertility, however, has the strongest independent effect on the spatial differentials in neonatal mortality rate. This is suggestive of the increased risk associated with high parity and short pregnancy interval.