Achieving sustained improvements in health outcomes remains a challenge for sub-Saharan Africa, where diarrhea remains a leading cause of death in children under the age of five. This paper examines the impact of foreign aid to the health sector on diarrhea mortality in children under five in 47 sub -Saharan African countries, using panel data on the sectoral allocation of official development assistance in conjunction with country -level data on health outcomes. After controlling for fixed effects and the potential endogeneity of health aid, we find that increased health aid and increased public health expenditure are associated with lower diarrhea mortality in children under five. In addition, health aid increases government spending on health, suggesting that the overall impact of health aid on diarrheal death rates could exceed the direct effect. Furthermore, increased access to improved sources of water and sanitation are important in reducing child mortality from diarrhea.