The invention relates to a method for preserving the stability of a hemoglobin blood substitute comprising maintaining the hemoglobin blood substitute in an atmosphere substantially free of oxygen. The method for preserving a deoxygenated hemoglobin blood substitute comprises maintaining the deoxygenated hemoglobin blood substitute in an oxygen barrier film overwrap package. In one embodiment, the package comprises a transparent laminate material comprising an oxygen barrier layer and a polyolefin layer, wherein the laminant has a thickness of between about 0.001 and about 0.01 inches (or about 0.0254 to about 0.254 millimeters) and an oxygen permeability of less than about 0.01 cubic centimeters per 100 square inches (or about 0.01 cc per 645 square centimeters) over 24 hours at 1 atmosphere and at about 23 C. The oxygen barrier layer comprises ethylene vinyl alcohol. Aso provided herein is a preserved deoxygenated hemoglobin blood substitute comprises a deoxygenated hemoglobin blood substitute and an oxygen barrier film overwrap package. The package comprises a transparent laminant material comprising an oxygen barrier layer and a polyolefin layer. Said oxygen barrier layer has an oxygen permeability of less than about 0.01 cubic centimeters per 100 square inches (or about 0.01 cc per 645 square centimeters) over 24 hours at 1 atmosphere and at about 27 C. room temperature, wherein the deoxygenated hemoglobin blood substitute is sealed within the overwrap package. In one embodiment, the oxygen barrier layer comprises ethylene vinyl alcohol.