Abstract: A control system for a road grader adapted to maintain the working edge of the grader blade in a preset datum plane so as to establish a uniform graded condition of the surface worked by the blade, regardless of the inclination assumed by the motor grader or the relative angular position of the blade itself. The system includes grade sensor means mounted adjacent one end of the blade to follow a pre-selected grade datum, slope sensing means mounted in fixed relation with the blade for keeping the blade at a predetermined slope with rotation sensing means mounted on the blade supporting ring or circle to detect the relative angular position of the blade. The rotation sensing means provides a correction signal for maintaining the slope angle of the blade at a value which will keep the "cross slope" of the surface established at a predetermined value regardless of the rotary position of the blade relative to the direction of travel.