Drawing on field data gathered during the course of Transport Canada's Fully Restrained Occupant Study (FROS), the current limits of protection afforded vehicle occupants restrained by conventional three-point seat-belt assemblies in side impacts are examined. The sample under consideration comprises 98 restrained passenger vehicle occupants involved either in a near side or a far side impact, each of whom sustained at least one injury at the AIS 2 or greater severity level (1976 AIS Dictionary). A detailed description of the pattern of injury to this subset of occupants and the damage sustained by the vehicle is presented. The principal mechanisms of injury for various body region groupings are discussed, with special attention being given to the incidence of side compartment intrusion. Other factors influencing injury potential such as occupant age and vehicle size are also discussed.In the case of near side impacts, the data suggest the need for greater attention to be paid in vehicle design to the load path developed in vehicle-to-vehicle collisions so as to minimize the degree of lateral compartment intrusion. Measures aimed at increasing the degree of lateral restraint provided occupants in far side impacts also need to be explored. Both subsets of the victim population would benefit from improvements in side door integrity and interior padding. In comparison to frontal impacts, the mechanisms of injury in side impacts are more varied and complex. Assessment of vehicle performance in lateral impacts may be difficult to realize through a single test on a complete vehicle.