Aim: The present study was designated to evaluate the oxidative stress biomarkers in male rat following oral repetitive administration of 0.1 LD50 of the herbicide bromoxynil. Methodology: Animals were orally received four doses of 0.1 LD50 of bromoxynil every other day. Twenty-four hours after the last oral dosing, all rats were killed by decapitation. Blood, brain, liver, and kidneys were taken for determination of TBARS, lactic dehydrogenase, catalase and alkaline phosphatase. Results: TBARS were found to be significantly increased in the liver, kidneys and brain where they were 390.20, 293.80, and 287.03% of control, respectively. In case of serum it was insignificantly increased to 162.88% of control value. Lactic dehydrogenase activity was significantly enhanced in serum and liver comparing with the control values (119.49 and 114.12%) and insignificantly enhanced in kidneys and brain (105.17 and 107.40%). Catalase activity was increased in all tissues where the enhancement was significant in both of serum and liver (122.68 and 119.99%, respectively) and insignificant in case of kidneys and brain (112.55 and 105.12%, respectively). Alkaline phosphatase activity in serum, liver, kidneys and brain was found to be elevated. These values were significant in liver and kidneys (113.47 and 121.14%, respectively) while they were insignificant in serum and brain (109.91 and 114.46%, respectively). Conclusion: Therefore, the herbicide bromoxynil could produce significant alteration in the lipid peroxidation and activities of some antioxidant enzymes and producing cellular oxidative damage in male rats following repetitive oral dosing.