The effect of mechanical properties on wear resistance of Si3N4 - SiC composite materials with different portions of SiC strengthening phase was investigated. Properties of monolithic silicon nitride were compared to ceramic composites consisting of Si3N4 matrix with 10 and 20 vol.% SiC. The SiC strengthening phase had a positive effect on the hardness of Si3N4 - SiC ceramic composite materials. Wear resistance of tested ceramic materials was mainly influenced by their fracture toughness. The highest wear resistance value was achieved for material with the highest fracture toughness. Worn surfaces of all experimental ceramic materials were damaged by both microcutting and microcracking mechanism. Microcracking was the predominant wear mechanism mainly at ceramic composites. The wear resistance of SiC-Si3N4 ceramic composites can be described by the model W ~ HV/KIC.