Even though cerebral fat embolism develops rarely after long bone fracture, it may be very important complication because it can be fatal and the early detection is not easy. Neurologic symptoms include confusion, restlessness, disorientation, seizure, and stroke with focal deficits. High intensive T2 signal MRI of the brain is most sensitive for diagnosis of cerebral fat embolism. We report a case of cerebral fat embolism diagnosed after external fixation of ankle open fracture in a 46 year old woman patient with multiple fracture.