A camshaft adjuster for motor vehicles has an oscillating motor having a rotor that is fixedly connected to a camshaft and further having a stator surrounding the rotor. The rotor is rotatable relative to the stator. At least one connecting part acting by at least one of positive engagement and force transmission is provided on a camshaft having cams. The rotor has a base member that is fixedly mounted on the connecting part. The base member has a diameter that is different from a diameter of a circle circumscribing the cams of the camshaft.