Two new spiro-lanostane triterpenoids, antrolactones A and B (1 and 2), along with polyporenic acid C (3), were isolated from an EtOAc-soluble extract of Antrodia heteromorpha culture medium, and the chemical structures of the new compounds were elucidated by application of NMR, MS, and ECD spectroscopic techniques. All isolated compounds exhibited inhibitory effects on receptor activator of nuclear factor-kappaB ligand-induced osteoclastogenesis.