The fretting wear behaviour of Ti-6Al-4V is experimentally investigated using a cylinder-on-flat specimen arrangement for different loads, strokes and numbers of fretting cycles, including partial slip and gross sliding conditions. An elastic-plastic, finite element (FE) based, incremental wear simulation approach is employed to study the evolution of the surface and sub-surface fretting variables, using a kinematic hardening (continuum) plasticity model to represent the cyclic plasticity behaviour. The predicted evolution of plastic deformation and fretting variables, such as contact pressure, relative slip, sub-surface stresses and critical-plane Smith-Watson-Topper (multiaxial) fatigue parameter, due to the simulated wear are compared with the observed wear scar characteristics and locations of crack initiation. It is shown that the characteristics of predicted plastic strain and damage accumulation are significantly different for the gross sliding and the partial slip cases and that the differences can be correlated with the observed differences in surface morphology and surface cracking. It is shown that the location of plasticity due to shear yielding at the surface promotes wear across the contact region for the gross sliding case and at the stick-slip interface for the partial slip case. (C) 2009 Elsevier B.V. All rights reserved.