Microstructure, microhardness and tribological properties of laser hardened GCr15 steel were investigated in this paper. The wear resistance under lubricated sliding conditions was compared between specimens treated with laser and those of conventionally hardened. The tribological properties of laser surface-quenched GCr15 steel specimens were slightly better due to the effects of the microstructure hardening, high hardness and toughness, with the wear rate (in the order of 10-6mg/Nm) lower than that of the conventionally treated specimens. At the steady state, the frictional coefficient of laser-treated samples had no obvious difference from that of the conventionally treated samples. The wear mechanism for both cases was similar, generally involved surface fatigue wear and slight abrasion wear. LeiQ.K. Liu S. Lei Introduction H. Li In recent years, among the various surface modification methods, laser-induced surface modification has gained much attention for achieving the desired properties for applications. This method is mainly used for ferrous alloys which undergo martensitic transformation and thus form a very hard surface layer with negligible surface roughness and distortion. Some ideas demonstrated that the wear rate at a particular contact pressure can be strongly influenced by the microstructure of the steel, but there is also contrary idea that under the conditions of mild wear, the microstructural constituents of steels have no significant influence on the wear rate, although they affect the rate of severe wear. Previous studies of the authors demonstrated that under the dry sliding wear conditions, laser surface-hardened specimens of ferrous alloys exhibited enhanced wear resistance than conventionally hardened specimens. The aim of the study is to investigate the lubricated sliding wear behaviors of laser surface hardened GCr15 steel specimens and to compare the effect of the different microstructure compositions for laser transformation hardening with those of conventionally hardened and quenched. Moreover, the wear properties of the GCr15 steel and its corresponding wear mechanism under the lubricated wear conditions will also be studied.