Recent studies have demonstrated that liposome treatment of red blood cells (RBCs) leads to improved recovery and membrane integrity following cryopreservation protocols. However, the effect of liposome treatment on hypothermically stored RBCs has not been previously investigated. The current study has investigated whether liposome treatment could modify the membrane quality and deformability of hypothermically stored RBCs. Unilamellar liposomes were synthesized using an extrusion protocol. Three lipid bilayer compositions were investigated: 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC):PE:PS (8:1:1); 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC):PE:PS (8:1:1); and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC):PE:PS (8:1:1). RBCs were treated with liposomes and subsequently stored for 42 days in HEPES-NaCl buffer and saline-adenine-glucose-mannitol. RBC quality was assessed by percent hemolysis, mean corpuscular volume (MCV), and RBC deformability (ektacytometry). DOPC and DMPC liposome treatment resulted in destabilization of the RBC membrane. Percent hemolysis values for DMPC-treated RBCs were higher than untreated controls throughout storage (P<0.05). DOPC-treated RBCs showed elevated levels of hemolysis compared to controls from day 21 of storage onward (P<0.05). In addition, DOPC and DMPC-treated RBCs were less deformable than untreated controls from days 21(P=0.02) and 14 (P<0.001) of storage onward respectively. [We suggest that these changes in RBC hemolysis and deformability are due to cholesterol extraction from the RBC membrane into the liposome fraction.] In contrast, DPPC-treated RBCs maintained hemolysis, MCV, and deformability values comparable to untreated controls. Future research addressing the optimal liposome composition for stabilizing the RBC membrane at cold temperatures could lead to effective strategies to combat the RBC membrane hypothermic storage lesion and ultimately improve the quality of hypothermically preserved blood.