The objective of this study was to establish the spatial distribution of the early neonatal mortality rate (0-3 days) in the municipality of Rio de Janeiro for 1995-1996, identifying the best explanatory factors for spatial variations. By considering Rio de Janeiro's 153 neighborhoods as ecological units of analysis, socioeconomic and maternal indicators were analyzed according to place of residence. Spatial statistical analysis was performed using the Cliff & Ord methodology, appropriate for lattice data. From the 0-3 day mortality thematic map, we clearly identified two clusters of high early neonatal mortality rates. Spatial dependence was also confirmed by the statistical results of the spatial analysis. The variables that explain the clusters are the proportions of "adolescent mothers", "slum-dwellers", and "heads of households below the poverty level". Spatial statistics provided a better understanding of the geographic distribution of early neonatal mortality and suggested potential hypotheses for further investigation, which could support preventive programs and contribute to a decrease in infant mortality.