The tolerance to abrupt linear deceleration (-Gx) and the subject interaction with an air bag plus lap belt and air bag only restraint systems were investigated. Twenty adult male baboons comprised the test pool. Peak sled decelerations ranged 8.6-123 g.The results indicated that the tolerance to impact (LD50) utilizing an air bag with or without lap belt was in excess of 120 g. The severest injuries were attributable to the lap belt, and included rupture of the rectus abdominus and quadriceps femoris muscles plus diaphragmatic tearing. There were no significant injuries to subjects restrained with only an air bag.Excellent linear correlations were established between peak lap belt forces and maximum sled deceleration. Comparative evaluation of the air bag restraint with a previously reported lap belt study was made when applicable.