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We have evaluated the feasibility of a newly developed single-use, magnetically levitated centrifugal blood pump, Med Tech Mag- Lev, in a 3-week extracorporeal membrane oxygenation ( ECMO) study in calves against a Medtronic Bio- Pump BPX-80. A heparin- and silicone-coated polypropylene membrane oxygenator MERA NHP Excelung NSH- R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the Med Tech group and two in the Bio- Pump group. Under general anesthesia, the blood pump and oxygenator were inserted extracorporeally between the main pulmonary artery and the descending aorta via a fifth left thoracotomy. Postoperatively, both the pump and oxygen flow rates were controlled at 3 L/min. Heparin was continuously infused to maintain the activated clotting time at 200-240 s. All the Med Tech ECMO calves completed the study duration. However, the Bio- Pump ECMO calves were terminated on postoperative days 7 and 10 because of severe hemolysis and thrombus formation. At the start of the Med Tech ECMO, the pressure drop across the oxygenator was about 25 mm Hg with the pump operated at 2800 rpm and delivering 3 L/min flow. The PO2 of the oxygenator outlet was higher than 400 mm Hg with the PCO2 below 45 mm Hg. Hemolysis and thrombus were not seen in the Med Tech ECMO circuits (plasma-free hemoglobin [ PFH] < 5 mg/d L), while severe hemolysis ( PFH > 20 mg/d L) and large thrombus were observed in the Bio- Pump ECMO circuits. Plasma leakage from the oxygenator did not occur in any ECMO circuits. Three-week cardiopulmonary support was performed successfully with the Med Tech ECMO without circuit exchanges. The Med Tech Mag- Lev could help extend the durability of ECMO circuits by the improved biocompatible performances. [ABSTRACT FROM AUTHOR]