Free radicals are known to play important role in pathophysiology of hepatic disorders andantioxidants are employed along with other chemotherapeutic agents in treatment of suchdiseases. In search of natural antioxidant, successive extracts of Hypericum (H.) hookerianum(Family: Hypericaceae) were evaluated by in vitro and in vivo methods. Extracts of aerial parts ofH. hookerianum were subjected for 1,1-diphenyl 2-picryl hydrazyl radical scavenging activity(DPPH assay), nitric oxide radicals scavenging assay and thiobarbituric acid reactive substances(TBARS) assay. Methanolic extract was found to be more active than other extracts in DPPH andin vitro TBARS assay with IC50 at 5.82 ± 1.33 µg/ml and 49.78 ± 3.79 µg/ml respectively. Whilepetroleum ether extract showed more potentials in scavenging the nitric oxide radicals with IC50220.97 ± 2.69 µg/ml. The administration of CCl4 to the control animals caused decrease in the levelof catalase and superoxide dismutase, together with significant increase in the level of TBARS inliver and kidney. Reversal of these changes towards normal group was observed byadministration of H. hookerianum methanolic extract at 50 and 100 mg/kg body weight, whileother extracts were found to be less active.