Phytochemical examination of the leaves of Alnus maximowiczii Call, one of the indigenous Alnus species grows in Korea, has led to the isolation of three flavonoids. Structure of these flavonoids were elucidated as quercetin-3-O-$eta$-D-glucopyranoside (1) , quercetin-3-O-$alpha$-L-rhamnopyranoside (2) and myricetin-3-O-$alpha$-L-rhamnopyranoside (3) respectively by means of physico-chemical and spectral evidences.