This study investigates the relationship between fertility and child mortality in Kwale district. Our first objective was to estimate the total fertility rate (TFR), the mean closed birth interval (MCBl) and child mortality q(2) using 1979 census data by division, education, marital status and residence differentials. Simple correlation analysis was then used to establish the relationship existing between birth interval and child mortality in the district. The results show that the length I of average birth interval and child mortality (q2) are negatively related though weakly. Further analysis using a sample of children from three locations in Kwale district included in the Child Survival and Development Baseline Survey (1987), show that the length of the previous birth interval and the subsequent birth interval have a significant impact on infant/child mortality whether duration of breastfeeding is taken into account or not. However, long previous birth intervals are favourable to survival at childhood while long subsequent intervals reduce the risk of mortality in infancy. Also, the age at which supplementation starts is an important determinant of child survival in Kwale District