This work explores the effect of surface modification of stainless steel with a carbon nitride (CNx) film, under sliding wear of the UHMWPE/steel. Wettatibility of CNx coatings is assessed by means of the sessile drop method using two different liquid media. Microhardness and stiffness of CNx coatings are estimated by depth-sensing indentation. The sliding performance of UHMWPE against stainless steel and CNx was evaluated using a pin on disk tribometer. It is demonstrated that CNx surface properties are quite different from those of stainless steel, with a concomitant substantial reduction of the coefficient of friction of UHMWPE/CNx in comparison with the one of UHMWPE/steel under sliding conditions. Even tough imposed sliding conditions do not conduct to wear mass loss in UHMWPE, wear track patterns against steel and CNx are quite different.