Safety belt use has dramatically increased in the past decade in North America because of safety belt use laws. Underarm use of shoulder belts is a means of relieving neck irritation and other complaints from shoulder belts but may result in serious or fatal injuries. Loads far in excess of the injury tolerance of the lower chest and upper abdomen are imposed by the shoulder belt in the underarm position. Six recent cases are presented in which fatal injury was caused by underarm use of shoulder belts. Lacerations of the liver, spleen, intestines, mesentery, diaphragm, and aorta, and spine injury have occurred in accidents, most of which should have been survivable. The motoring public must be warned that underarm use of shoulder belts is hazardous and may cause fatal injuries in otherwise survivable accidents.