The Tribological behavior of Polystyrene Crystal disc sliding against a steel 100Cr6 ball with a radius of 5mm over a range of loads (1-5N) and speeds (12.5-63mm/s) was investigated using a ball-on-disc tribometer under unlubricated conditions. All the specimens were used as obtained from injection molding. For this purpose, we monitored the evolution of the friction coefficient and the wear rate as a function of sliding speed and normal load applied. The worn surfaces were examined by Scanning Electron (SEM) and optical microscope. Several wear mechanisms were observed: plastic deformation, abrasion in the track, and adhesion at the edge of the track. The mechanisms were found to depend on speed and load. The wear rate is of the order of 10-2mm3/N.M, which may explain that the wear is of a severe type.