Effects of tempering temperature and shot peening on fatigue behavior of SAE 1045 steel are reported. Tensile and fatigue property measurements are reported for samples tempered and shot peened at 300 and 550°C. Microstructural studies and fracture surface observations were carried out by optical and scanning electron microscopes. The experimental results showed that, fatigue strength increases with decrease of tempering temperature and shot peening treatment. SEM analyses indicated that all three stages of fatigue fracture affected by tempering treatment whilst shot peening treatment only have an effect on the crack initiation stage.