Antioxidant effects of natural antioxidants in 73%-lean ground beef patties during refrigeration were studied. Samples were subject to an antioxidant treatment (pomegranate extract, grape seed extract, butylated hydroxyanisole, or no treatment) and an irradiation treatment (0 or 1.5 kGy) before being evaluated for both uncooked and cooked indicators of lipid oxidation. Chemical evaluation of antioxidant activity were determined over 9 d through measurement of thiobarbituric reactive substances values. Physical evaluation of antioxidant activity was monitored by changes in physical color and sensory odor analysis on patties before and after cooking. Butylated hydroxyanisole extended the induction period of oxidation in all unirradiated beef patties better than the natural antioxidants. Panelists were able to distinguish a difference (in terms of oxidation attributes) between patty samples of different antioxidant and irradiation treatments while samples were uncooked, but unable to distinguish a difference between patties after cooking.