Vitamin E is one of the major membrane protectants against reactive oxygen species ( ROS) and lipid peroxidation (LPO). The study aimed at determining the optimum dose of vitamin E to reverse free radical-mediated oxidative damage on motility, viability and LPO of bulls’sperm. Fresh semen of five local crossbred bulls was suspended in 2.9% sodium citrate, divided into equal fractions and subjected to vitamin E treatment (0, 1, 2, 2.5 mM) in the presence or absence of oxidative stress inducer, i.e ferrous ascorbate (FeAA, containing 150 μM FeSO4 and 750 μM ascorbic acid). All sperm suspensions were incubated at 37°C for 2 h. Treatment with FeAA reduced sperm motility and viability, but increased the LPO. All doses of vitamin E increased sperm motility and viability,but reduced LPO. However, 2 mM vitamin E was most effective. In conclusion, vitamin E reduced the LPO caused by FeAA, and improved sperm motility and viability in vitro under induced oxidative stress.