The invention relates to a rotor (1, 71) for a camshaft adjuster, comprising a substantially annular rotor basic body (3, 73) which has an end surface (11, 91) with a contour (15, 89) which extends in an axial direction, wherein the contour (15, 89) has an asymmetry such that precisely one position is predefined for the axial attachment of the rotor basic body (3, 73) to a camshaft (31, 112). A rotor (1, 71) with a contour (15, 89) of this type makes centering on a camshaft (31, 112) possible in a manner which is cost-neutral and can be easily implemented in terms of manufacturing technology. Furthermore, the invention relates to a camshaft adjusting system (111) with an above-mentioned rotor (1, 71).