The increasing interest in powerful biological activity of plant phenolics and flavonoids outlined the necessity of determining their contents in Dryopteris cochleata leaves. The present investigation comprises, estimation of total phenolics, flavonoids, flavonols, tannins, carbohydrates, vitamin-C and protein content accompanied by an important in vitro antioxidant assays like DPPH-radical scavenging activity and reducing power for various leaf extracts. Quantitative screening provided a gateway to assess all the estimations, among which the significant role was played by the acetone extract. IC50 and EC50 of the in vitro assays of acetone depicted striking evidence in contrast to the other extracts. Supportively, GC–MS analysis revealed that many useful constituents indicating D. cochleata leaves could be useful for preparation of neutraceuticals as potent antioxidant to treat various human diseases and its complications.