In this study, the effect of vitamin C and E supplementation on lung injury and performance of runners were analyzed. Using a randomized, double-blinded, crossover design, nine runners participated in two experimental trials: a 2-week Vitamin trial (vitamin C = 500 mg/day + vitamin E = 100 IU/day) and a 2-week Placebo trial. At the end of each supplementation period the runners performed an 8-km time-trial run in a hot (31°C), humid (70% rh), and ozone-polluted (0.10 ppm O3) environmental chamber. Nasal lavage and blood samples were collected pre-, post-, and 6-h post-exercise to assess antioxidant status and CC16 as lung injury marker. Higher plasma (pre- and post-exercise) and nasal lavage (post-exercise) antioxidant concentration were found for the Vitamin trial. Nevertheless, this did not result in performance differences (Vitamin trial: 31:05 min; Placebo trial: 31:54 min;P= 0.075) even though significant positive correlations were found between antioxidant concentration and improvement in time to complete the run. CC16 was higher post-exercise in the Placebo trial (P< 0.01) in both plasma and nasal lavage. These findings suggest that antioxidant supplementation might help to decrease the lung injury response of runners when exercising in adverse conditions, but has little effect on performance.