Chemical composition is developed for new high-strength wear-resistant steels with guaranteed yield strength of 1200, 1500, and 1700 MPa. Phase transformations, microstructure, and mechanical properties are studied after steel quenching and low-temperature tempering. It is shown that fine carbides 7–43 nm in size with a volumetric density of 13·1020 m−3, formed in lath martensite with lath width of 100–200 nm and dislocation density of (4–5)·1014 m−2 after tempering at 200–300°C, provide the required combination of strength characteristics and toughness. Formation of grain boundary cementite and that between laths, caused by breakdown of residual austenite, has an embrittling effect.