This paper examines the relationship between health aid and infant mortality, using data from 118 countries between 1973 and 2004. Health aid has a beneficial and statistically significant effect on infant mortality: doubling per capita health aid is associated with a 2 percent reduction in the infant mortality rate. For the average country, this implies that increasing per capita health aid by US$1.60 per year is associated with 1.5 fewer infant deaths per thousand births. The estimated effect is small, relative to the 2015 target envisioned by the Millennium Development Goals. It implies that achieving the MDG target through additional health aid alone would require a roughly 15-fold increase in current levels of aid.