A series of controlled deceleration experiments was performed with 37 human male volunteers to determine, if possible, human tolerance to lateral impacts while restrained in a seat with a lap belt. The subjects were exposed in 50 different experiments at average impact G of 3.25 to 9.02 for durations of 0.3 to 0.1 seconds. No permanent physiological changes were noted. Minor physical complaints were reported by 50 per cent of the subjects when exposed to 6.25 average G or more. Increasing danger from lateral flexion of up to 30° from the vertical halted the experiments at the 9.02 average G.