A propolis sample from the western Andean slopes of the Maule Region, Chile, showed free radical scavenging activity and inhibited the enzyme xanthine oxidase "in vitro". Six flavonoids were isolated as the main active constituents of the sample. 5,7-dihydroxyflavone 4, 3,5,7-trihydroxyflavone 6 and 5,7-dihydroxyflavanone 1 displayed a strong free radical scavenging effect. At 50 mg/ml, compounds 6 and 1 inhibited the enzyme xanthine oxidase by 95 and 86%, respectively.