Objective: Terfezia claveryi is a dark brown color truffle and has been usedextensively in human diet in Turkey. Therefore; it is an important issue to determinetheir biological activities and toxicity. This study aims to investigate the antioxidant andanti-urease effects of T. claveryi methanol extracts and to evaluate the genotoxicityof each extract.Methods: The antioxidant activities of methanol extracts were examined by2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS) and ferric reducing/antioxidant power (FRAP) methods. Theamount of total phenolic compounds contained in the extracts was determined usingthe Folin-Ciocalteu reagent (FCR) method. Anti-urease activities of methanol extractswere evaluated by indophenol method. In addition, potential DNA damaging effects ofT. claveryi extracts on human lymphocytes were determined by the alkaline cometassay.Results: UM extract exhibited higher DPPH radical scavenging activity than MMextract [the concentration of the substance which provides the inhibition of 50% of theradical (IC50):0.77±0.01 mg/mL, 1.17±0.02 mg/mL, respectively, p<0.0001] however,lower activity than standard (p<0.0001). Both extracts in different concentrations ofT. claveryi caused DNA damage (p<0.0001) compared with solvent control DMSO.Also, total comet scores was higher in cells which had been incubated with MMextract (p<0.05). UM extract exhibited higher ferric reducing and anti-urease activitythan MM extract but not found statistically different; also activities of both extract werefound lower than positive controls of each methods (p<0.0001).Conclusion: T. claveryi methanol extracts induced genotoxicity on lymphocytes andshowed very low antioxidant activity compared to standards. This preliminary studyshould be confirmed with further studies and in diferent cell lines.