Introduction: Although pharmacological antioxidants have previously been investigated for a prophylactic effect against exercise oxidative stress, is not known if α-lipoic acid supplementation can protect against DNA damage following high intensity isolated quadriceps exercise. This randomised controlled investigation was designed to test the hypothesis that fourteen days of α-lipoic acid supplementation can attenuate exercise-induced oxidative stress. Methods: Twelve (n=12) apparently healthy male participants (age 28 ± 10 years, stature 177 ± 12 cm and body mass 81 ± 15 kg) were randomly assigned to receive either a daily supplement of 1000mg of α-lipoic acid (2 × 500mg tablets) for fourteen days (n = 6) or receive no supplement (n = 6) in a double blinded experimental approach. Blood and muscle biopsy tissue samples were taken at rest and following the completion of 100 isolated and continuous maximal knee extension (minimum force = 200 N, speed of contraction = 60°/sec). Results: Exercise increased mitochondrial 8-OHdG concentration in both groups (P <0.05 vs. rest) with a concomitant decrease in total antioxidant capacity (P <0.05 vs. rest). There was a marked increase in blood total antioxidant capacity following oral α-lipoic acid supplementation (P <0.05 vs. non-supplemented), while DNA damage (Comet assay and 8-OHdG) lipid peroxidation and hydrogen peroxide increased following exercise in the non-supplemented group only (P <0.05 vs. supplemented). Exercise increased protein oxidation in both groups (P <0.05 vs. rest). Conclusion: These findings suggest that short-term α-lipoic acid supplementation can selectively protect DNA (but not in muscle mitochondria) and lipids against exercise-induced oxidative stress.