This study is developed based on the hypothesis that the deficiencies of project of the package for the automobile s rear passengers, as well as of the rear seat safety-belt itself, from the ergonomic point of view, cause discomfort and constrain people to its usual use. Therefore, its rejection or misuse have been subjecting the passengers to injuries and even to death, in case of accidents. Concerning the importance of the safety-belt s use, especially at the rear seat, the concept and the magnitude of all forces involved toward the protection of the occupants of a vehicle are explained. The legislation history of safety belts is very related with the evolution of the product, except in Brazil. An analysis is done about the ergodesign of the safety-belt s components, its complements and supplements; and particularly its ergodesign in the rear passengers package of the best selling automobiles in the market. Interviews with taxi-drivers, a pensioner fireman and victims of accidents who were at rear seat, became to support the confirmation of the hypothesis. The video recording of the real behaviour of passengers, in addition to the answers of a questionnaire applied to each one of them, had also ratified part of the ergonomic problems detected in this study, which main causes are: absence of emergency release device, absence of the retrator device, absence of the pretensioner device, lacks of more points of anchorage for the belt and the presence of a central occupant in the rear seat of a vehicle. Therefore, we conclude that to reduce injuries and deaths of the automobile users, in current accidents, it is urgent to extend the good solutions for the safety belt of some cars to all of them and to remodel its respective legislation.