In this investigation, a number of anesthetized rhesus monkeys, baboons, and chimpanzees were subjected to a +Gz rectangular deceleration-time history. The parameters of deceleration versus average time duration were plotted as a function of spinal trauma to come up with a series of sensitivity curves based on spinal injury for three families of sub-human primates. The locus, distribution, type, and severity of vertebral body fracture was distinguished on post-impact roentgenographs. The primates were euthanized and the process of documenting and interpreting spinal trauma was repeated following necropsy and water maceration of the soft tissue. The mechanics of vertebral injury were identified. Normal skeletal geometry and proportionate torso kinesiology of the rhesus monkey, baboon, and chimpanzee and man were compared. The peculiarities and consistencies in injury distribution and their variations were interpreted in terms of distinctive vertebral morphology and functional kinesiology of each animal model. The distinguishing variations in injury patterns and their distribution was related to the scatter of human vertebral injury as reported in aircraft escape system accelerations, crash decelerations, and clinical statistics.THIS PAPER DEALS WITH spinal injury due to abrupt +Gz decelerative forces. Its purpose is to comparatively describe the biomechanical torso skeletal response of the rhesus monkey, baboon, and chimpanzee to a rectangular deceleration-time history in an attempt to establish a basis for a whole body interspecies scaling relationship among primates*. More specifically, this paper deals with the type, locus, and distribution of spinal injury as related to the vertebral bodies. It provides additional understanding and knowledge as to the comparative nature of torso skeletal geometry, kinesiology, and spinal injury among primates. These results are compared to human spinal column morphology, injury modes, severity and levels. The overall goal of this effort is to come up with a rational basis for using subhuman primates as a model to explain and predict human injury in biodynamic environments.