A healthy 23-year-old man wearing a three-point seat belt was driving a car not equipped with an airbag at approximately 40 km/hr. The driver lost control of the car, crashed through the guardrail, and ran off a cliff. After rolling over several times, the car landed upside down on a river bank 30 meters below the cliff. When the paramedics arrived, they found the man dead, with his head in the driver's seat and his lower extremities in the front passenger seat. Although the fastened seat belt had loosened, the diagonal belt had tightened against the front and the left side of the neck. Because the police could not immediately determine the cause of death, a forensic autopsy was performed 22 hours after death. Autopsy findings revealed ligature marks on the surface of the neck, hemorrhages in the muscles of the neck, petechial hemorrhages in palpebral conjunctivae and viscera, dark red liquid blood in the heart cavities, and visceral congestion. The autopsy concluded that the man died of strangulation by the seat belt. In this case, the loose belt allowed the body to move, and subsequently the diagonal belt applied external pressure to the neck while the car was rolling over. Although there have been several reports of neck injuries due to diagonal belts, this is the first report of strangulation by a properly used three-point belt in a roll-over vehicle accident. 3 figures and 14 references