Rabdosia nervosa (Hemsl.) C. Y. Wu & H. W. Li is a perennial herb mainly distributed in the south of China. Its stems and leaves have been used to treat hepatitis, fester, and eczema in Chinese folk medicine [1]. In our effort to use the biological activity of natural products to find the lead molecule of drugs from Chinese medicinal plants, we report herein the isolation, structural elucidation, and biological activities of seven diterpenoid compounds from an alcoholic extract of the stems and leaves of Rabdosia nervosa, including longikaurin E (1) [2], lihsienin A (2) [3], 6 ,7 ,11 -trihydroxy-7 ,20-epoxy-ent-kaur16-en-15-one (3) [4], shikokianin (4) [5], effusanin A (5) [6], taibaihenryiin A (6) [5], and taibaihenryiin B (7) [5]. To the best of our knowledge, compounds 2, 3, 4, 6, and 7 are reported for the first time from Rabdosia nervosa. The stems and leaves of Rabdosia nervosa were collected from Tianmu Mountain, Zhejiang Province, China in June 2008 and were identified by Prof. Lu-Huan Lou. A voucher specimen (#20080616) was deposited in the College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, P. R. China. The dried powder of the stems and leaves of Rabdosia nervosa (5.3 kg) was soaked three times with 95% EtOH at room temperature. Solvent was removed by evaporation at reduced pressure, and the residue was successively fractioned with EtOAc and n-BuOH. The residue of the EtOAc fraction was subjected to column chromatography over silica gel. The column was eluted with a gradient of petroleum ether–EtOAc (1:0–0:1) and EtOAc–CH3OH (1:0–0:1). The crude compound was purified by repeated chromatography on a silica gel column with CH2Cl2–CH3COCH3, CH2Cl2–(CH3)2CHOH, and CHCl3–CH3COCH3 to obtain the pure compound. The structures of the compounds were established using spectral data and comparisons with the literature except for compound 3, which had been mentioned in a Japanese patent [4] but whose spectroscopic data and formula (C20H26O5) did not agree with the structure given in the description. We obtained data on the cytotoxic activity of diterpenoids 1–7 for HepG2 (human liver cancer cells), HeLa (human cervical cancer cells), and k562 (human erythromyeloblastoid leukemia cells). The standard MTT test according to published recommendations [7] was used to determine the IC50. Table 1 presents the results (with cis-diaminodichloroplatinum(II) (CDDP) as the positive control). The results revealed that all the tested substances decreased HepG2, HeLa, and k562 cell proliferation, except for compound 2, which lack the -methylidene five-membered ketone thought to be very important for cytotoxic activity [8, 9], and which showed weak activity, as expected. Longikaurin E (1), C22H30O6, colorless needle crystals, mp 264–267 C. IR (KBr, , cm–1): 3375, 1720, 1717, 1644, 1240, 923. EI-MS 390 [M]+. 1H NMR (500 MHz, TMS, C5D5N, , ppm, J/Hz): 6.58 (1H, d, J = 10, 6 -OH), 5.99, 5.31 (each 1H, s, H-17a/b), 5.44 (1H, t, J = 4.7, H-11 ), 4.40 (1H, dd, J = 9.2, 1.8, H-20a), 4.29 (1H, m, H-6 ), 4.22 (1H, dd, J = 9.2, 1.1, H-20b), 2.06 (3H, s, OAc), 1.27 (3H, s, CH3-18), 1.05 (3H, s, CH3-19). 13C NMR (125 MHz, TMS, C5D5N, , ppm): 209.6 (C-15), 153.0 (C-16), 117.1 (C-17), 96.1 (C-7), 74.9 (C-6), 68.7 (C-11), 68.6 (C-20), 60.0 (C-9), 59.1 (C-8), 53.4 (C-5), 41.6 (C-3), 37.9 (C-12), 37.1 (C-10), 34.4 (C-1), 34.1 (C-18), 33.8 (C-4), 31.1 (C-13), 27.6 (C-14), 22.7 (C-19), 18.7 (C-2), OAc: 169.6, 21.6.