The biotransformation of naringin and naringenin was investigated using cultured cells of Eucalyptus perriniana. Naringin (1) was converted into naringenin 7-O-beta-D-glucopyranoside (2, 15%), naringenin (3, 1%), naringenin 5,7-O-beta-D-diglucopyranoside (4, 15%), naringenin 4',7-O-beta-D-diglucopyranoside (5, 26%), naringenin 7-O-[6-O-(beta-D-glucopyranosyl)]-beta-d-glucopyranoside (6, beta-gentiobioside, 5%), naringenin 7-O-[6-O-(alpha-l-rhamnopyranosyl)]-beta-D-glucopyranoside (7, beta-rutinoside, 3%), and 7-O-beta-D-gentiobiosyl-4'-O-beta-d-glucopyranosylnaringenin (8, 1%) by cultured cells of E. perriniana. On the other hand, 2 (14%), 4 (7%), 5 (13%), 6 (2%), 7 (1%), naringenin 4'-O-beta-D-glucopyranoside (9, 4%), naringenin 5-O-beta-D-glucopyranoside (10, 2%), and naringenin 4',5-O-beta-D-diglucopyranoside (11, 5%) were isolated from cultured E. perriniana cells, that had been treated with naringenin (3). Products, 7-O-beta-D-gentiobiosyl-4'-O-beta-D-glucopyranosylnaringenin (8) and naringenin 4',5-O-beta-D-diglucopyranoside (11), were hitherto unknown.