The purpose of this study is to investigate the effects of the physical vapor deposition (PVD) and gas-nitriding on the fatigue properties of titanium alloy (Ti-4.5Al-3V-2Mo-2Fe). Rotational bending fatigue tests were performed on five types of specimens; that are uncoated, TiN coated, gas-nitrided, annealed after TiN coating, and Ti-TiN coated. We obserbed the fracture process. The results are summarized as follows : 1) The fatigue strength of the gas-nitrided specimen was decreased less than that of the untreated and TiN coated specimens. This is because the matrix grain size increased because of a high temperature nitriding process (800℃ for 4 hours). 2). Fatigue limit of Ti-TiN coated specimens that was maked to progress fatigue strength of titanium alloy (Ti-4.5Al-3V-2Mo-2Fe) was decreased less than that of TiN coated specimens. This is because : firstly Ti coated surface was highly rough, secondly the thickness of Ti film was much smaller than that of diflusion layer of gas-nitrided specimen.