Pistacia khinjuk is one of the fifteen known species of Pistacia belonging to Anacardiaceae family. Keeping in view the possible therapeutic utility of this genus and the lack of literature on this plant, this study involves phytochemical investigation of P. khinjuk and its antioxidant activity. The phytochemical investigation was conducted on crude methanolic extract and its fractions namely, n-hexane, chloroform, n-butanol, ethyl acetate and aqueous. Total phenolic contents and flavonoids were also determined by phosphomolybdenum and ferric thiocyanate method in crude extract and its fractions. The results of phytochemical investigation indicated the presence of alkaloids, tannins, flavonoids, saponins, triterpenoids, cardiac glycosides, carbohydrates, proteins and sterols in the crude extract of P. khinjuk. Crude extract and its fractions exhibited remarkable antioxidant activity. This study showed that the crude extract and its fractions have potent antioxidant activity, among all ethyl acetate showed 1.109 ± 0.029 the highest activity. This research concluded that crude extract of P. khinjuk and its fractions contained phenolic and flavonoid compounds that show significant antioxidant activity.