The influence of the surface modification treatment on the rolling contact fatigue and the scuffing capacity of rollers was examined by two cylinder test under oil lubrication. The surfaces of test rollers were modified by the electroless Ni-P alloy plating and the sulfurizing. The rolling contact fatigue strength and the scuffing capacity of the surface modified rollers were larger than those of the non-coated rollers. In the fatigue test the failure mode of both the surface modified rollers and the non-coated rollers was the spalling caused by subsurface cracking. The friction coefficient of the Ni-P plated rollers was smaller than that of the non-coated rollers, and the surface roughnesses of the modified rollers were decreased with increasing wear of modified layers. The small friction coefficient and the small roughness contribute to the improvement of the scuffing capacity, and moreover they might reduce the surface contact stresses and the rolling contact fatigue strength might be improved.