Numerous studies of the collision performance of seat belt restraint systems have been conducted by vehicle safety researchers. The findings of such studies have shown conclusively that three-point, lap and shoulder, seat belt systems are extremely effective in mitigating the trauma sustained by vehicle occupants in the vast majority of collisions. Typically, these results form the basis of government programmes designed to increase seat belt usage rates in the motoring public. The emphasis of such programmes is on encouraging motorists to wear the available seat belts;​ however, seldom is there any stress placed on the need to wear the seat belt correctly. This paper presents a number of clinical case studies of motor vehicle occupants who have received injuries directly attributable to the improper use of occupant restraints. In the opinion of the authors the severity of the injuries suffered by the restrained occupants would have been reduced had the seat belt systems been worn correctly. In several of these cases, improperly worn seat belts probably resulted in more severe injuries than would have been expected had the occupants been unrestrained. These conclusions underscore the desirability of not only promoting the use of seat belts, but also their correct use.