Impact biomechanics is an area of research primarily associated with the protection of vehicular occupants. It is also concerned with the prevention of sports-related injuries and with injuries due to falls. It deals mainly with loads that have high rates of onset and with durations that are considerably less than one second. The objectives of impact biomechanics are to understand how a body region is injured in an impact and to seek means to minimize injury through environmental modifications. A secondary objective is to ensure that such environmental modifications do not become a secondary source of injury. Impact biomechanics can be broadly categorized into four areas. They are Mechanisms of Injury, Human Response to Impact, Human Tolerance to Impact, and Development of Human Surrogates for Impact Simulation. Each area plays a role in the design of automotive restraint systems and interior structures and in the understanding of how injury is caused so that effective countermeasures can be taken to minimize the injury. This paper describes advances made in all four areas of impact biomechanics over the last two decades. Areas of current research interest are also discussed. They point to the need for new data and further research work in impact biomechanics.