The invention relates to a device for variable control of the gas exchange valves of an internal combustion engine, of which at least one gas exchange valve is triggered by a cam of a camshaft, which cam has a cam contour with a circular portion of the cam bottom and a cam apex portion. For variably adjusting the cam contour, a pressure-fluid-actuated piston guided by the cam and retractable and extensible radially continuously, is provided which on its end forms at least a part of the cam apex portion.