Abstract: The friction and wear characteristics and wear mechanisms of several commercial dental composites were investigated. Thus the friction and wear behaviors of the composite specimens made from commercial dental composites Compoglass, F2000, Elan, and Dyract-AP sliding against Si_3N_4 under unlubricated condition in a ball-on-disc configuration were evaluated using a ball-on-disc friction and wear tester. The microstructures and worn surface morphologies of the composite specimens were examined using a scanning electron microscope. The contents of glass bead fillers in the composite specimens were determined in an attempt to analyze the effect of the fillers on the friction and wear behavior. It was found that the F2000 had a quite high friction coefficient, while the composites Compoglass and Dyract-AP showed better wear resistance than F2000 and Elan under the same experimental conditions. The four kinds of dental composites were dominated by crack propagation and brittle fatigue of glass fillers.