Data from 88% of United States institutions that perform cardiopulmonary bypass surgery were analyzed to determine the type, time of storage, anticoagulant, and amount of blood used. The frequency with which cardiopulmonary bypass procedures are performed has more than doubled in the last five years, demanding an ever increasing proportion of the national blood resource. An average of nearly eight units of blood were used per case in 1971. Problems in procurement continue, as a marked number of surgical teams still require fresh, heparinized blood in relatively large amounts. Since the increasing use of saphenous vein bypass surgery may create a prodigious demand upon the blood resource of this country, new policies and practices are needed to reduce the amount of exogenous whole blood used per patient.