Background. Cerebral embolization during cardiopulmonary bypass is an important cause of neurologic injury. This study determined whether an endoaortic baffle catheter (Cardeon Cobra Catheter; Cardeon Corporation, Cupertino, CA) could substantially reduce cerebral embolization. in a swine cardiopulmonary bypass model. Methods. Sixteen 60 kg pigs underwent cardiopulmonary bypass; 8 animals with the Cobra baffle (Cardeon Corporation, Cupertino, CA) deployed, and 8 with the same cannula without baffle deployment. The animals were embolized with 72,000 fluorescent microspheres (97 to 100 mum) at normothermia. At the end of the experiment, the brains were removed and microspheres were isolated from eight regions. Results. During embolization, the two groups were equivalent with regard to pump flow, mean arterial pressure, temperature, Hgb and PaCO2. Deployment of the Cobra baffle reduced embolization to every brain region. Deployment of the baffle reduced total brain embolization by 89%. There was a mean of 61 +/- 60 emboli per gram in the control animals and 7 +/- 24 emboli per gram in those animals in which the baffle was deployed. Conclusions. Cerebral embolization is profoundly reduced by use of the Cobra baffle aortic cannula. The application of this device may reduce postcardiac surgical neurologic injury.