A new lanostane-type triterpene, 29-hydroxypolyporenic acid C (8), was isolated from the dried sclerotia of Poria cocos together with eight other known compounds pachymic acid (1), dehydropachymic acid (2), 3-acetyloxy-16α-hydroxytrametenolic acid (3), polyporenic acid C (4), 3-epi-dehydropachymic acid (5), 3-epi-dehydrotumulosic acid (6), tumulosic acid (7), and dehydrotumulosic acid (9). The compounds were identified by spectral analysis and comparison with spectroscopic data reported in the literatures. Although none of the nine (1 to 9) compounds showed promising antioxidant activity, 1 through 6 and 8 showed good cytotoxicity against human lung cancer cell line A549 and human prostate cancer cell line DU145. Interestingly, all these compounds exhibited better cytotoxicity towards A549 than DU145 cells.