Wear tests of H13 steel with various tempering microstructures were performed under atmospheric conditions at room temperature (RT), 200 A degrees C, and 400 A degrees C. The wear characteristics and wear mechanisms of various tempered microstructures of the steel were focused by investigating the structure, morphology, and composition of the worn surfaces. Under atmospheric conditions at RT, 200 A degrees C, and 400 A degrees C, adhesive wear, mild oxidation wear, and oxidation wear prevailed, respectively. The wear rate at 200 A degrees C was substantially lower than those at RT and 400 A degrees C due to the protection of tribo-oxides. In mild oxidation wear, the tempered microstructures of the steel presented almost no obvious influence on the wear resistance. However, in adhesive wear and oxidation wear, the wear resistance strongly depended on the tempered microstructures of the steel. The steel tempered at 600-650 A degrees C presented pronouncedly lower wear rates than the one tempered at 200-550 or 700 A degrees C. It can be suggested that the wear resistance of the steel was closely related with its fracture resistance.