reactive oxygen and nitrogen species are produced in the body both in normal and pathological processes and can alter cell redox and affect cell functions. Exercise training is able to modulate oxidant/ antioxidants balance. In this study, we aimed to evaluate expression of antioxidant enzymes genes in the liver and cardiac tissues of rats that performed high-intensity interval training (hIIT) and received L-carnitine (LCar). Thirty-two male Wistar rats were were randomly assigned into 4 groups (n = 8) as follows: 1. Untreated control; 2. The group that received LCAR (200 mg/kg/day i.p.); 3. The group that performed HIIT on a readmill (5 days/week for 4 weeks); 4. The group that received LCAR and performed HIIT. At the end of the study, liver and cardiac tissues were excised and used to quantify glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT) and NF-κB genes expression by real-time PCR. It was found that both in LCAR and HIIT groups GPX, SOD and NF-κB (P < 0.01) expression in cardiac and liver tissues was significantly increased compared to the indices in the control group. In LCAR-HIIT group SOD and NF-κB expression in the liver was significantly increased compared to the group that received LCAR only (P = 0.046). our results showed that LCar supplementation is useful to improve oxidative status in cardiac and liver tissues of rat during exercise training.