This study was designed to investigate the in vitro and in vivo antioxidant activities of inulin. The in vitro assays demonstrated that the antioxidant activities of inulin, including the DPPH radical scavenging activity, ABTS scavenging activity and ferric reducing power, were weak and significantly lower than those of Vitamin C (P < 0.05). The influence of dietary supplementation with inulin on the antioxidant status of laying hens was evaluated with in vivo antioxidant assays. The results indicated that inulin supplementation quadratically improved the egg production rate of the laying hens (P < 0.01). The antioxidant enzyme activities in the serum, including SOD, CAT, and GSH-Px, and the total antioxidant capacity increased quadratically as inulin levels increased (P < 0.001). The levels of MDA in the serum decreased quadratically as inulin levels increased (P < 0.001). These findings suggest that inulin has the potential to improve the antioxidant status of laying hens.