In the case of frontal or rear collision, the vehicle seat and safety belt act as a retaining system that is supposed to protect the person and prevent injury as much as possible. A double shoulder belt (harness belt) was integrated into the seat as a 4-point belt in order to examine the possibilities of improving personal protection. Due to the transfer of the test requirements for the safety belt to the seat with integrated safety belt, the load level in the direction of motion increases considerably. The normal test conditions were increased by using a 95% dummy rather than a 50% dummy. According to these requirements, a seat back with seat back adjuster was designed, built, and tested.The test showed that by proper deformation of the seat back, the load on the person is reduced and that the seat with integrated 4-point belt provides an improvement of the retaining system for the frontal as well as the rear crash.