Abstract: OBJECTIVE To study the Maca extract on endurance of rats and the effect of blood antioxidant enzyme activity. METHODS The Wistar rats treated with/without the Maca extract (8.0, 16.0, 32.0 g·kg^-1) were freely swimming in the circulating water flow daily for 15 d. On the 16th day of experiment, the blood was collected. The endurance, blood malondialdehyde(MDA), superoxide dismutase(SOD), glutathione peroxidase(GSH-Px) level were determinated.RESULTS Compared with those swimming rats without extract treatment, when rats were administered with Maca extract at the doses of 8.0, 16.0, 32.0 g·kg^-1, the swimming time before sinking and the total swimming time were increased by 34.38%, 84.25%, 126.07%(P<0.01) and 37.42%, 47.03%, 107.24%(P<0.01), respectively. The times of sinking was decreased by 17.65%, 33.28%, 55.50%(P<0.01 or P<0.05), respectively. The MDA content in the blood of the rats treated with 8.0, 16.0, 32.0 g·kg^-1 was reduced by 34.63%, 54.13% , 63.73% respectively(P<0.01), while the levels of SOD and GSH-Px were enhanced by 67.78%, 108.25%, 154.49%(P<0.01) and 48.57%, 110.28%, 154.86%(P<0.01), over those of rats without treatment, respectively. CONCLUSION The maca extract has resist fatigue, enhance exercise capacity effect. The mechanism is associated with reduced blood MDA, improve the activity of SOD and GSH-Px.