The purpose of this study is to determine the in vivo autologous 24-hour post-transfusion recovery and survival of red blood cells stored in CPD/Optisol preservation solution. Red blood cells will be stored for 42 days. The blood will be held for 72 hours at 1-6 degrees prior to plasma separation and addition of the AS-5 solution. Survival will be determined using 51 Chromium labelling autologously reinfused red blood cells.