Background/Aims: During storage, units of human red blood cells (pRBCs) experience membrane destabilization and hemolysis which may cause harm to transfusion recipients. This study investigates whether inhibition of acid sphingomyelinase could stabilize erythrocyte membranes and prevent hemolysis during storage. Methods: Human and murine pRBCs were stored under standard blood banking conditions with and without the addition of amitriptyline, a known acid sphingomyelinase inhibitor. Hemoglobin was measured with an electronic hematology analyzer and flow cytometry was used to measure erythrocyte size, complexity, phosphatidylserine externalization, and band 3 protein expression. Results: Cell-free hemoglobin, a marker of hemolysis, increased during pRBC storage. Amitriptyline treatment decreased hemolysis in a dose-dependent manner. Standard pRBC storage led to loss of erythrocyte size and membrane complexity, increased phosphatidylserine externalization, and decreased band 3 protein integrity as determined by flow cytometry. Each of these changes was reduced by treatment with amitriptyline. Transfusion of amitriptyline-treated pRBCs resulted in decreased circulating free hemoglobin. Conclusion: Erythrocyte storage is associated with changes in cell size, complexity, membrane molecular composition, and increased hemolysis. Acid sphingomyelinase inhibition reduced these changes in a dose-dependent manner. Our data suggest a novel mechanism to attenuate the harmful effects after transfusion of aged blood products.