Antioxidant activities, total phenolic and total monomeric anthocyanin contents were determined in mahonia berry extracts in different solvents. The methanol:water extract was purified to obtain anthocyanin and non-anthocyanin phenolic fractions, one at a time, and antioxidant activities of these fractions were also analyzed. Total phenolic and monomeric anthocyanin contents in mahonia berries were ranged from 1.30 (chloroform extract) to 1049.40 (methanol extract) mg GAE/100 g FW, and 40.68 (water extract) to 380.99 (ethanol extract) mg/100 g FW, respectively. The main phenolic and anthocyanin in mahonia berries were chlorogenic acid (373.12 mg/100 g FW), and cyanidin-3-O-glucoside (253.40 mg/100 g FW), respectively. The antioxidant activity of the anthocyanin fraction of the berries was approximately twofold higher than that of the phenolic fraction. The contribution of phenolic and anthocyanin compounds to the antioxidant activity of mahonia berries was greater than 83%. Phenolic compounds, especially anthocyanins, are the major antioxidant compounds found in mahonia berries.