Objective:To identify the phytochemical constituents ofAmorphophallus campanulatus (A. campanulatus) tuber and to evaluate its antioxidant potential throughin vitro andin vivo models. Methods: Phytochemical screening andin vitro antioxidant activities ofA. campanulatus tuber n-hexane extract (ACHE) and methanolic extract (ACME) were evaluated using DPPH, hydroxyl radical, reducing power and total antioxidant capacity assays. The total phenolic and flavonoid contents were also investigated. The protective potential of two different doses ofACME (125 and250 mg/kg) was also evaluated against thioacetamide (TAA) induced oxidative stress in rats. Silymarin used as a standard drug control. Hepatotoxicity was assessed by quantifying the serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). The antioxidant potential ofACME were also evaluated by the estimation of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (Thiobarbituric acid reactive substances) in hepatic and renal tissues. Histopathologic changes of liver were also evaluated.Results:In vitro studies revealed thatACME has higher antioxidant and radical scavenging activity thanACHE, which may be attributed to its higher phenolic and flavonoid content.ACME significantly prevented the elevation of serumAST, ALT, ALP, LDH, and tissue malondialdehyde levels(P < 0.05). Hepatic and renalGSH, GST, GR, GPx, and catalase levels were remarkably increased by the treatment with the extract. Quantification of histopathological changes also supported the dose dependent protective effects ofACME.Conclusions: The results do suggest thatA. campanulatus tuber could be considered as a potential source of natural antioxidant.