In this research, rotating bending fatigue test at minimum to maximum stress ratio of R=-1 was used for investigating the fatigue behavior of Ti-6Al-4V alloy. Both smooth and notched specimens, with elastic concentration factor, kt, of approximately 3.6 and 4.1 were used for this purpose.In addition, the effect of variation in ultimate tensile strength, UTS, on the fatigue behavior of this allo...