We experienced a case of retrobular hemorrhage during cardiopulmonary bypass. Following factors are suspected as the cause retrobulbar hemorrhage in this patient; l ) Rupture of preexisting AV malformation or aneurysm. 2) Accidental high flow to innominate artery by Coanda effect or miscannulation, 3) Obstruction of right jugular venous drainage and therefore cerebrofacial flow is increased, 4) Increase bleeding tendency during cardiopulmonary bypass. Fortunetely, patient has no neurologic complication and well recovered from retrobulbar hemorrhage.