Bioactivity-guided fractionation led to the successful isolation of antiosteoporotic components, i.e. physicion (1), rubiadin-1-methyl ether (2), 2-hydroxy-1-methoxy- anthraquinone (3), 1,2-dihydroxy-3-methylanthraquinone (4), 1,3,8-trihydroxy-2-methoxy- anthraquinone (5), 2-hydroxymethyl-3-hydroxyanthraquinone (6), 2-methoxyanthraquinone (7) and scopoletin (8) from an ethanolic extract of the roots of Morinda officinalis. Compounds 4-8 are isolated for the first time from M. officinalis. Among them, compounds 2 and 3 promoted osteoblast proliferation, while compounds 4, 5 increased osteoblast ALP activity. All of the isolated compounds inhibited osteoclast TRAP activity and bone resorption, and the inhibitory effects on osteoclastic bone resorption of compounds 1 and 5 were stronger than that of other compounds. Taken together, antiosteoporotic activity of M. officinalis and its anthraquinones suggest therapeutic potential against osteoporosis.