Child mortality differentials according to water supply and sanitation in many urban areas of developing countries suggest that access to piped water and toilet facilities can improve the survival chances of children. The central question in this study is whether access to piped water and a flush toilet affects the survival chance of children under five in urban areas of Eritrea. The study uses data collected by the Demographic and Health Survey (DHS) project in Eritrea in 1995. The results show that while the unadjusted effect of household environment (water supply and toilet facility) is large and statistically significant during the post-neonatal and child periods, it is relatively small and statistically insignificant during the neonatal period. The effect of household environment remains substantial during the post-neonatal and child periods, even when other socioeconomic variables are held constant. However, the household environment effect totally disappears during the neonatal period when the socioeconomic factors are controlled for.