Abstract: A solution suitable as a hypothermic blood substitute for replacing blood in euthermic subjects during surgery are provided. The blood substitute contains a purge solution and a maintenance solution, the latter of which is useful for organ preservation. The purge solution contains an aqueous solution of electrolytes at physiological concentrations, a macromolecular oncotic agent, a biological pH buffer effective under physiological and hypothermic conditions, a simple sugar, and a substrate for the regeneration of ATP. The maintenance solution contains a second aqueous solution of electrolytes containing potassium ions at a concentration range of from 35 to 45 mM, sodium ions at a concentration range of from 80 to 120 mM, magnesium ions at a concentration range of from 2 to 10 mM, chloride ions at a concentration range of from 15 to 20 mM, and calcium ions at a concentration range of from 0.01 to 0.