As of January 1992, all back seat passengers in France, in cars equipped with rear seat belts, will be required to buckle up. For side rear seat positions, the use of 3-point belt systems, which have been installed in French vehicles for approximately the last 15 years, will certainly improve passenger protection as they are known to be highly effective. However, almost none of the current vehicles are equipped with a seat belt for the central rear seat position. Vehicle owners, of course, have the possibility of having central 2-point rear seat belts installed after they buy the car, but it has only been recently that car manufacturers have been installing these seat belts on the production line. Given that the effectiveness of these seat belts is often a subject of controversy in the US, will it save lives in France if all occupants of the central rear seat position wear them (using restraining system adaptations appropriate for young children)? The study of past research in this field, accident data, and testing with post mortem subjects and dummies, has shown that the systematic use in the central rear position of a lap belt (even with appropriate restraint adaptations for young children) by all passenger, will result in an increase in the number of occupants killed and seriously injured for accidents on the whole. The number of serious injuries to occupants which can be avoided with such a belt, mainly by preventing occupant ejection, will be lower than the number of additional serious injuries which will be observed in frontal impact accidents. Of course this conclusion, which is based on a given occupant age distribution (accident data from 1980), could change if there were a change in this distribution. For example, if significantly more young occupants (younger than 7) use this central rear position (35% in the studied sample), the protection they would receive with a restraint device adapted to the two-point lap belt could offset the aforementioned risk. It might even decrease the number of seriously injured.