Abstract: This invention provides an improved method for prolonging the shelf life of transfusible red blood cells by decreasing the effective osmolality of the suspending solution and increasing the intracellular pH of the cells prior to storage thereof. This invention also provides methods whereby the intracellular pH may be increased. These methods include collecting the cells in an anticoagulant at pH 7.0 or higher and/or washing, diluting or resuspending the cells prior to storage thereof in a biologically compatible buffered solution that contains at least one non-penetrating or substantially non-penetrating anion or non-electrolyte and is substantially free of chloride ions.

Abstract: The present invention discloses a hypotonic suspension medium and a method for prolonged storage of red blood cells at about 4.degree. C. The suspension medium comprises about 80-150 mM glucose, 30-80 mM mannitol, 6-90 mM potassium citrate, 1-5 mM adenine and 10-200 mM ammonium chloride or acetate in an aqueous solution having a pH of about 6.8 to 7.2 and an osmolarity of about 180-220 milli-osmolar. The suspension medium and the method of the present invention allow viable storage of red blood cells at about 4.degree. C. up to 125 days or more.