Fat embolism syndrome is manifested by the fat globule presence in the pulmonary and systemic circulation. A 34-year-old man was involved in a motor vehicle accident with a fracture of the left femur and avulsion fracture of the left posterior cruciate ligaments. He developed signs and symptoms that suggested an early diagnosis of fat embolism syndrome. Intravenous methylprednisolone administration was administered as part of the treatment. The role of methylprednisolone in a patient with fat embolism syndrome is controversial due to unproven effectiveness. In this case, fat embolism syndrome after a femur fracture was treated successfully with methylprednisolone.