Prunus avium (PA) seeds oil was extracted with pet. ether in a Soxhlet for two days to give an oily residue and analyzed by GC/MS. 24 compounds were detected and identified in which γ-sitosterol (18.57%), erucylamide(12.36%)and are the main. A part from oily residue was treated with hot acetone to precipitate the acetone insoluble constituents in which di 2-ethylhexyl phthalate and octadecanol are main and acetone soluble fraction which saponified to afford the unsaponifiable materials and fatty acids which were identified by GC/MS and /or GLC analyses. The flavonoids were isolated from the ethyl acetate fraction and identified as naringenin, 7,3',4'-trimethoxy quercetin and lucenin-2 in addition to p-coumaric acid. The structure of these compounds were established using different spectroscopic techniques. The antioxidant activity of different extracts and fractions (pet. ether, fatty alc., fatty acids, 70% methanol, chloroform and ethyl acetate) were tested using a DPPH free radical assay. It was found that the 70% methanol extract and ethyl acetate fraction exhibited remarkable activity (88.43 and 78.39 % respectively).