Our overall objective in this research is to improve red blood cell (RBC) transfusion practices for anemic, critically ill infants. This project has received support from two granting agencies: 1) The Thrasher Foundation, entitled, "Red Blood Cell Recovery and Survival Following Transfusion in Infants;" and 2) NIH PPG Grant P01 HL046925, Project 1 entitled, "Red Blood Cell Survival Following Transfusion In Infants." Abstracts for both are included below. This project will be completed in two phases: