The role of polyphenols and flavonoids in prevention of cellular damages carried out with the oxidative stress is well documented. In the present experiment, we determined the polyphenols and flavonoids concentrations of three extracts (ethanol 70%: V/V, methanol 80%: V/V and distilled water extracts) of carob pulp mature (Ceratonia siliqua L.) and their in vitro and in vivo antioxidant activity. A significant dose-dependent anti-free radical activ-ity of ethanolic extract of carob (EEC) was related to the highest polyphenol content (44.74 mg QE/mL) and to the in vitro antioxidant activity (EC50 = 0.28 mg/mL) of this extract. LC-MS /MS analysis of the EEC have shown the presence of several phenolic compounds as well as many types of flavonoids. The in vivo experiment brought out the significant effect of the daily EEC oral pre-treatment of rats, 30 min before AlCl3 administration for 28 d on the improvement of the total blood antioxidant capacity. These results suggest that the carob pulp contain many substances having in vitro and in vivo antioxidant effects, and which could be used as natural food additives in order to preserve food quality.