Phytochemical screening and antioxidant activities in different solvent extracts of onion was carried out. The extracts were subjected to various chemical Test for phytochemical constituents.Total phenolic contents were evaluated using FolinCiocalteu method and their antioxidant activity was assayed through «in vitro» radical scavenging activity usingDPPH· assay, FRAP and ABTS. The phytochemical screening of this study indicated the presence of steroids, flavonoids, alkaloids, saponnins, and catechic tannins. The average total polyphenol content of hydroethanolic extracts was significantly (P<0.05) higher than in the hexane, ethyl acetate and dichloromethane extracts. The order of effectiveness (IC₅₀) of the plant extracts the potent inhibitors was hydroethanolic extract, followed by Dichloromethane, ethyl acetatewhile the least was the hexane extract, When using (DPPH, ABTS and FRAP). This shows that onion organic solvent extracts especially the hydroethanolic extracts may be a potent source of natural antioxidant and can be used in the management of diseases associated with oxidative stress is justified