This study aimed to evaluate the effects of vitamin C and vitamin E on antioxidant capacity and immune function in oxidative-stressed breeder roosters. One hundred twenty 45-week-old Lveyang black-boned breeder roosters were randomly assigned to 5 dietary treatments, including negative control group (NC), positive control group (PC), and 3 trial groups, which were fed the diets containing 300 mg/kg VC, 200 mg/kg VE, or 300 mg/kg VC and 200 mg/kg VE (VC+VE). At 47 wk of age, the positive control and trial groups were subcutaneously injected 3 times every other d with dexamethasone (DEX) 4 mg/kg of body weight, the negative control group was injected with saline. The experiment lasted for 35 d. The results showed that at 50 wk of age, average daily feed intake of birds challenged with DEX significantly increased (P < 0.05). During post-stress recovery period (52 wk of age), dietary supplemental VE or VC+VE notably increased body weight under oxidative stress (P < 0.01). Oxidative stress induced by DEX could significantly decrease superoxide dismutase (SOD), IgM, antibody titer of ND and mRNA expression of SOD or glutathion peroxidase activity (GSH-Px), increase serous malondialdehyde (MDA) (P < 0.05). Supplementation of VC or VE significantly decreased serous MDA, and increased SOD under oxidative stress (P < 0.05). Supplementation of VC or VE, or their combination significantly increased the relative expression of GSH-Px mRNA when compared to the oxidative-stressed control treatment (P < 0.05), whereas did not alleviate the relative expression of SOD mRNA (P > 0.05). Therefore, the results suggest that addition of 300 mg/kg VC, 200 mg/kg VE or their combination could improve antioxidant ability and immune performance in oxidative-stressed breeder roosters through up-regulating the expression of GSH-Px gene.