To screen the phytochemicals and investigate the antioxidant potential of Acorus calamus rhizomes by in vitro methods. Ethyl acetate extract of Acorus calamus rhizomes were initially screened for phytochemicals , further total phenolic content , total antioxidant activity, reducing power assay, free radical scavenging assays such as DPPH, Superoxide anion, Hydroxyl radical scavenging assays. The qualitative phytochemical analysis reveals the presence of phenolics, flavonoids, alkaloids, carbohydrates, tannins, terpenoids and proteins. The total phenolic and flavonoid content were found to be 52.62 ± 0.32 mg/g Gallic acid equivalents, 54.2 ± 0.15 mg Quercetin /grams equivalents respectively. The extract has shown the maximum antioxidant and scavenging activity against free radicals as DPPH, superoxide anion, and hydroxyl radicals at 1000µg/ml. The ethyl acetate extract of A. calamus has shown the dose dependent antioxidant and scavenging activities against free radicals. © 2015 By IYPF All rights reserved.