A multi-scale modelling approach for fretting wear, which integrates a macro-wear simulation tool and a micro-asperity model, is presented. The finite-element-based macro-wear simulation tool predicts local distributions of contact pressure and slip and simulates material removal from the fretting interface. The former information, together with local thickness of the debris layer, forms inputs to the asperity model, so that cyclic plastic deformation underneath the debris layer can be calculated. By knowing the local plastic deformation, the movement of the debris layer into the substrate within the macro-wear simulation tool can be determined according to a plasticity-enhanced oxidation model. The constants required by the multi-scale modelling approach are identified from fretting tests and the simulated results are validated against test measurements.