In this study, the effect of static strain aging on the fatigue behavior of a mild steel (S275JRC) was evaluated. For this purpose, the 5 % prestrained mild steel was aged at a temperature of 160 degrees C for different intervals. The aging behavior was determined primarily for the as-received (AR) as well as in the homogenization and normalizing heat treated (H+N heat treated) condition. The yield stresses before and after aging process as well as the hardness values of the aged steels were measured for the assessment of the strain aging progress. The dynamic mechanical behavior of strain aged samples was also determined by fatigue test under the dynamic loads. An increase in the yield strength due to strain aging and hardness induced improvement in fatigue strength of the steel were observed.