The nitrided layer is extremely thin due to the existence of a passive film at the surface of austenitic stainless steel. In order to accelerate the diffusion of nitrogen into the material, a fine particle peening (FPP) treatment was introduced prior to gas nitriding (pre-FPP treatment). The effects of pre-FPP treatment on gas nitriding behavior and fatigue properties of AISI 316 steel were evaluated. Surface microstructures of the pre-FPP treated specimens were characterized using a micro-Vickers hardness tester, scanning electron microscope (SEM), optical microscope, electron probe micro analyzer (EPMA) and X-ray diffraction (XRD). The pre-FPP treatment generated the local stratification pattern which has high dislocation densities. Therefore, nitrogen diffused into this unique structure, resulting in an increase of the surface hardness. Fatigue tests were conducted at room temperature using a rotational bending fatigue testing machine. The pre-FPP treated specimen showed the highest fatigue strength. After fatigue tests, fracture surfaces were observed using an SEM in order to investigate the high cycle fatigue properties.