The supernatant plasma remaining after factor VIII cryoprecipitate preparation is a most useful product and should not be returned to the plasmapheresis donor or to the refrigerator as factor VIII-poor whole blood. Stable coagulation factors are well preserved for up to 35 weeks at refrigerator temperature and for as long as one year in the frozen state. This enhances the usefulness of this product for treatment of patients with hemophilia B or with deficiencies of other stable coagulation factors. Preparation of the plasma from preselected donors of the type AB blood permits its use as a medium for reconstitution of packed cells for exchange transfusion, or as a volume expander. Moreover, use of this by-product reduces the cost of cryoprecipitate treatment for the patient with hemophilia A.