Objective : To evaluate the effects of the reactive oxygen species (ROS) generated with a xanthine (X) and xanthine oxidase (XO) system on sperm function, the change of sperm characteristics, lipid peroxidation, and DNA fragmentation in bovine spermatozoa. Materials and Methods: ROS were produced using a combination of 1000 uM X and 50 mU/ml XO. The ROS scavengers: superoxide dismu tase (SOD) (200 U/ml) and catalase (500 U/ml) were also tested. Spermatozoa were incubated for 2 hours in BWW medium with a combination of X-XO supplemented with or without ROS scavengers at $37^{circ}C$ under 5% $CO_2$ incubator. Sperm movement characteristics by CASA (computer-aided sperm analysis), HOST (hypoosmotic swelling test), Caionophore induced acrosome reaction, malondialdehyde formation for the analysis of lipid peroxidation, the percentage of DNA fragmentation using the method of TdT-mediated nick end labelling (TUNEL) by flow cytometry were determined after 2 hours incubation. Results: The action of ROS on bovine spermatozoa resulted in a decreased in capacity for sperm motility, Ca-ionophore induced acrosome reaction and membrane integrity, an increased in malondialdehyde formation and the percentage of sperm with DNA fragmentation. In the effects of antioxidant, catalase completely alleviated the toxic effects induced by the ROS in terms of sperm function and characteristics, however SOD exhibited no capacity to reduce the toxic effects. Conclusion: The ROS can induce significant damages to sperm functions and characteristics. The useful ROS scavengers can minimized the defects of sperm function and various damages of spermatozoa.