['Hypothermic storage (HS) of red blood cells (RBCs) leads to a progressive deterioration of cell quality. Mitigating these deleterious changes could allow maintenance or even an improvement of RBC in vitro quality. The aim was to determine the effect of a cold rejuvenation treatment of RBCs and in particular to assess the connection between ATP levels, RBC deformability, and morphology during RBC storage.', 'A pool-and-split design of leukoreduced CPD-saline-adenine-glucose-mannitol-packed RBC units was used to generate three groups: untreated controls, sham-treated units, and units treated with a cold (1-6 °C) rejuvenation solution on Day 28, 35, or 42 of cold storage. Units were followed until Day 49 of storage and assessed for ATP concentration, morphology, deformability, and other in vitro quality variables including hemolysis, pH, and supernatant potassium levels.', 'At every treatment time, rejuvenation was associated with a significant increase in intracellular ATP (p < 0.01). On Day 28, rejuvenation was accompanied by a significant decrease in deformability 1 week after treatment (p < 0.01). Rejuvenation on Day 28, but not Day 35 or 42, was also associated with a significant change in morphology (p < 0.01). Of the in vitro quality variables measured, most changed during cold storage, but differences among treatment groups were not observed.'] Does rejuvenation of ATP during storage reverse effects of the hypothermic storage lesion?