Fat embolism is a significant complication following total joint arthroplasty. Fat embolism syndrome has both pulmonary and neurologic manifestations that can be life threatening. But, with appropriate fluid management, adequate ventilation, and the prevention of hypoxemia, outcome is usually excellent. We experienced fat embolism following bilateral total knee replacement. A 65-year-old woman had a surgery under general anesthesia. There was no specific anesthetic problems during the operation. After bilateral tourniquet release, O2 saturation decreased to 85% and neurologic symptom was developed. With adequate supportive treatment including mechanical ventilation, she was cured without complication.