<p><strong>Objective: </strong>The current study was to deal the isolation and identification of secondary metabolites from <em>Polygonum equisetiforme</em> and evaluation of antioxidant activity of its extract.</p><p><strong>Methods: </strong>The methanol-water extract (7:3) of the air-dried aerial parts of <em>Polygonum equisetiforme</em> was fractionated and separated to obtain the isolated compounds by different chromatographic techniques. Structures of these compounds were elucidated by UV and 1D⁄2D H⁄ C NMR spectroscopy and compared with the literature data. The crude extract was evaluated for <em>in vitro</em> antioxidant activity using the 2,2 diphenyl dipicryl hydrazine (DPPH) method.</p><p><strong>Results: </strong>Ten secondary metabolites were isolated from <em>Polygonum equisetiforme</em> in this study. Of which three new flavonoids named as 3,5,7,2’,5’ pentahydroxyflavone 3-<em>O</em>-b-D-glucopyranoside (1), 3,5,7,2’,5’ pentahydroxyflavone 3-<em>O</em>-b-D-glucopyranoside 8 C-sulphated (2) and quercetin 3-<em>O-β</em>-D-glucucorinde 6''-methyl ester 8-sulphated (3) as well as quercetin 3-<em>O-β</em>-D-glucucorinde methyl ester (4), quercetin 3-<em>O-</em>β-D-glucopyranoside (5), quercetin 7-<em>O-β-</em>D-glucopyranoside (6),<em> </em>quercetin(7)<sub>, </sub>myricetin (8), <em>P</em><sub>-</sub>methoxy gallic acid methyl ester (9) and gallic acid (10). The antioxidant potential of <em>P. equisetiforme</em> extract was evaluated by investigating it's total phenolic and flavonoid content and DPPH radical scavenging activity whereby the extract showed significant antioxidant activity (IC<sub>50 </sub>= 37.45 μg/ml). The total phenolic and flavonoid content was found to be 130.79±5.502 and 45.8±1.63 μg/ml, respectively.</p><p><strong>Conclusion: </strong><em>Polygonum equisetiforme</em> is a promising medicinal plant, and our study tends to support the therapeutic value of this plant as an antioxidant drug.</p>