Abnormal serum urate levels are recognized as a critical factor in the progression of several chronic diseases. To evaluate the antihyperuricemic effect of Davallia formosana, the inhibitory activities of 15 isolated phytochemicals, including five novel compounds of 6,8-dihydroxychromone-7-C- β -d-glucopyranoside (1), 6,8,3',4'-tetrahydroxyflavanone-7-C- β -d-glucopyranoside (2), 6,8,4'-trihydroxyflavanone-7-C- β -d-glucopyranoside (3), 8-(2-pyrrolidinone-5-yl)-catechin-3-O- β -d-allopyranoside (4), and epiphyllocoumarin-3-O- β -d-allopyranoside (5), were examined against xanthine oxidase (XOD) and in a potassium oxonate-(PTO-) induced acute hyperuricemic mice model. The results indicated that compounds 3 and 5 significantly inhibited XOD activity in vitro and reduced serum uric acid levels in vivo. This is the first report providing new insights into the antihyperuricemic activities of flavonoid glycosides which can possibly be developed into potential hypouricemic agents.