Two new Steroidal alkaloids, named pengbeisine A and pengbeisine B, were isolated from the fresh bulbs of Fritillaria monatha Migo. along with a known alkaloid. The structures were characterized as 22,26-imino-17, 23-oxido-5 alpha-jerv-6-oxo-2 alpha,3 beta-diol and 22, 26-imino-17, 23-oxido-5 alpha-jerv-6-oxo-2 beta,3 alpha-diol on the basis of spectroscopic methods. (C) 2008 Yong Ming Luo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.