Diamond-like carbon (DLC) films were deposited on both the untreated and the prior carbon ion implanted Ti6Al4V alloys by plasma enhanced chemical vapour deposition (PECVD). The tribological behaviours were evaluated by conducting reciprocating wear tests against ZrO2 using a ball on disc tribotester. The effect of ion implantation dose and zone on mechanical and tribological behaviour of DLC films was studied by means of nanohardness and nanoscratch tester, SEM and three-dimensional surface profiler. The duplex treatment dramatically increased the surface hardness and bonding strength of film/substrate. Both carbon ion implantation and PECVD improved the wear resistance of titanium alloy, whereas the combined process of carbon ion implantation with the dose of 10(16) ions cm(-2) and PECVD offered the best wear resistance by a reduction of 94.3% in wear volume in comparison to untreated alloy. The cracks and deformations that induced local flaking failure under high contact stress played an important role in the wear and failure mechanisms.