A vehicle guidance system for assisting a driving lane change includes an object detection unit for detecting objects in a laterally adjacent rearward side space area of the vehicle. An analysis unit receives signals from the object detection unit and determines whether an object is situated in a dead angle section (blind spot) of the monitored rearward side space, or whether any such object in a section of the monitored rearward side space which is rearward beyond a dead angle section is moving forward at a higher speed than the system vehicle. If so, and if, in addition, it detects at the same time a lane change request pertaining to the corresponding side area, it activates a warning indicating unit for emitting a warning signal. According to the invention, a position detection device is provided which determines path data of the obstacle vehicle and the road geometry data, as well as the position of the system vehicle on the road. When the object detection unit detects an obstacle vehicle which is following in the rearward side space, corresponding to the covered distance recorded by the position detection device and the road geometry, a position assignment of the vehicle which is following is determined relative to the road.