Mannose and fructose as well as glucose have been shown to be effective for maintaining ATP and thus viability of stored red blood cells. Normal 2,3-DPG levels are desirable in stored red blood cells to provide the needed oxygen transport upon transfusion. ATP levels in sotred concentrated red blood cells in the new preservative, CPD-adenine (citrate-phosphate-dextrose-adenine) become critically low in the 5th week. In this study two hexoses and two pentoses are compared with dextrose in their ability to maintain ATP and 2,3-DPG. ATP levels were best maintained by fructose, then dextrose and mannose. ATP levels had fallen to critically low levels by four weeks with ribose and xylose. Red blood cell 2,3-DPG concentrations were also maintained by hexoses, with mannose being best, dextrose and fructose being similar. When ribose was used in addition to dextrose in CPD-adenine, ATP maintenance was improved and under the same conditions xylose improved 2,3-DPG maintenance. Fructose and mannose may be as useful as dextrose in citrate-phosphate preservatives for maintaining ATP and 2,3-DPG levels. Also, ribose and xylose may help the maintenance of ATP and 2,3-DPG, respectively, in CPD-adenine.