We report a postoperative patient who developed neurally mediated syncope, which was diagnosed using head-up tilt testing after the patient developed syncope in the intensive care unit. The patient had been misdiagnosed as having epilepsy since her childhood. Therefore, in patients with presumed epilepsy who present with syncope and have a nondiagnostic electroencephalogram, cardiac causes of syncope, such as neurally mediated syncope, should be considered.