Wheat bran was extracted successively with hexane, chloroform and ethanol. The antioxidant activity of each extract was measured using the thiobarbituric acid (TBA) test. The ethanol extract showed the highest activity, it caused 90% inhibition on the oxidative degradation of linoleic acid. For further evaluation of its activity, ethanol extract was added at two concentrations (0.02% and 0.05% of the beef fat level) to ground beef containing 20% fat. The aroma concentrates of the cooked beef samples containing the ethanol extracts or those containing commercial antioxidants BHA and BHT were isolated both before and after storage for one week at 4 degrees C. The oxime derivatives of the volatile carbonyl components isolated from the aroma concentrate of each sample were prepared and subsequently estimated by ultraviolet absorption at wavelength 212 nm for the total carbonyl oximes. The results showed that the ethanol extract has significant (P<0.05) effect in reducing rancidity in the stored beef samples in addition to decreasing the decomposition rate of the unsaturated fatty acids of the beef fat.