In multiple trauma, blunt carotid artery injuries (BCAIs) have occasionally been reported. However, bilateral blunt carotid artery occlusions (Grade 4 BCAIs) associated with multiple trauma are rare, and delays in diagnosis and treatment result in a lethal outcome. Here, we report our experience with bilateral carotid artery occlusions. A 76-year-old female suffered multiple traumas in a motor vehicle accident. On arrival at our hospital, she presented in a coma, with left mydriasis and unreactive pupils. Computed tomography (CT) showed bifrontal intracranial epidural hematoma and fractures of the facial bone and anterior skull base, and osteoplastic craniotomy was urgently undertaken for the epidural hematoma. However, the comatose state and unreactive pupils persisted during the post-operative course. Serial head CT findings showed progressive bilateral ischemic changes, and radiological examinations revealed bilateral internal carotid artery occlusions. We speculated that bilateral Grade 4 BCAIs had induced progressive cerebral infarctions. The patient partially responded to anticoagulation therapy with heparin infusion, but died of multiple organ failure on day 15. When bilateral progressive ischemic changes are observed in a patient with severe traumatic brain injury, bilateral Grade 4 BCAIs should be considered in the differential diagnosis. CT angiography as part of whole-body CT at admission may be effective for preventing delays in diagnosis and treatment of bilateral Grade 4 BCAIs.