Recently, it has been demostrated that large plastic strains imposed on a chip, during machining, results in significant microstructure refinement [1]. Titanium chip obtained by machining is found to have a nanocrystalline structure with ∼100 nm size grains. The hardness and strength of the nanostructures are seen to be substantially higher than those of microcrystalline titanium. In this work, the tribological behavior of this nanocrystalline titanium created by large strain machining is compared with that of conventional pure titanium. Tribological tests on titanium samples have been carried out in a pin-on-disk tribometer, sliding against AISI 52100 steel pins. The wear performance of the nanocrystalline titanium, is shown to be superior than the microcrystalline material. Wear mechanisms are discused from SEM observation of wear tracks, wear debris morphology and transfer tribolayers. Copyright © 2006 by ASME.