In this study, fatigue behavior of polypropylene fiber reinforced concrete has been studied under constant and variable amplitude loading. Crack length was measured during flexural fatigue test under three loads. Accordingly, damage curves were determined as function of stress levels. The results ascertained that the presence of 1 wt% polypropylene fibers considerably increases resistance against fatigue crack growth under constant amplitude loading. Under variable amplitude loading, it was found that the damage curve approach predicts the fatigue life with 13–15.8% estimation error, whereas linear model predicts the fatigue life with 36.8–56.5% estimation error.