Phytochemical screening, antioxidant activity in vivo and lipid peroxidation of 75 % ethanolic extract of young twigs and leaves of Caesalpinia bonduc were carried out by chemical test, and assessment of catalase and peroxidase activities and lipid peroxidation in Wistar rats after oral administration of different concentrations of the plant extract for ten days. Phytochemical screening of the extract revealed the presence of all major classes of phytochemicals: tannins, flavonoids, saponin, steroids, terpenoids, cardiac glycosides, glycosides, except phlobatannins. There were significant (p<0.05) graded increase in catalase and peroxidase activities and decrease in TBARS concentrations in the extract tested rats in comparison with normal control, Vitamin C and amodiaquine tested rats. The various pharmacological activities of C. bonduc may be due to its antioxidant activity