The oxygen transporting capability of an artificial oxygen carrier NRC was evaluated by employing it as a perfusate for total cardiopulmonary bypass. NRC is a type of liposome encapsulated hemoglobin. It has a particle size of approximately 220 nm, with a hemoglobin concentration of 5.6 g/dl and its P50 is controlled to 45 Torr. Male beagles were used in the experiment. Approximately 80% of the estimated circulatory volume was exchanged with NRC and total cardiopulmonary bypass was initiated. Arterial oxygen tension and carbon dioxide tension were controlled to 400 Torr and 40 Torr respectively. The perfused we heated to 37°C. The rate of flow was altered during the experiment. Oxygen consumption reached a plateau at 9.3 ml/kg/min where oxygen delivery was 14.9 ml/kg/min. At this point the oxygen consumed per gram of hemoglobin from NRC was equivalent to that from dog red blood cells. This indicated that almost an equal amount of oxygen was consumed from NRC in comparison to red blood cells. Regarding oxygen transporting capability, NRC could be considered a candidate for perfusate in cardiopulmonary bypass.