AbstractTwo novel flavanone glycosides, homoeriodictyol 7‐O‐β‐D‐[6‐(3‐hydroxybutanoyl)glucopyranoside] (viscumneoside IX; 1) and homoeriodictyol 7‐O‐β‐D‐[6‐(3‐hydroxybutanoyl)glucopyranosyl](1→2)‐β‐D‐glucopyranoside (viscumneoside X; 2), together with four known flavanoids, 2‐homoeriodictyol 7‐O‐β‐D‐glucopyranoside (3), viscumneoside I (4), viscumneoside III (5), and 4′,5‐dihydroxy‐3′‐methoxy‐7‐(2‐O‐α‐L‐rhamnopyranosyl‐β‐D‐glucopyranosyloxy)flavanone (6) were isolated from stems and leaves of Viscum coloratum. Their structures were elucidated on the basis of their NMR spectra, HR‐FAB‐MS data, and acid hydrolysis. Inhibitory effects of the four compounds 1–4 on the formation of osteoclast‐like multinucleated cells were investigated. As a result, all the four flavanoids showed significant inhibitory effects on the formation of osteoclast‐like multinuclear cells even at a low concentration of 2 μg/ml. The activities of 1–4 at such a concentration exceeded or approximated to that of elcitonin, the positive control drug at a concentration of 2 U/ml, suggesting that they may be of interest for the development of new anti‐osteoporosis drugs.