Three new diterpenoid alkaloids, liaconitine A (N-ethyl-1 alpha,6 alpha,16 beta,18-tetramethoxy-13 beta-ol-2,3-dehydroaconitane-8-acetate-14-anisoylate), B (N-ethyl-1 alpha,6 alpha,16 beta,18-tetramethoxy-13 beta-ol-2,3-dehydroaconitane-8,14-dianisoylate and C (N-ethyl-1 alpha,6 alpha,16 beta,18-tetramethoxy-8-ethoxy-13 beta-ol-2,3-dehydroaconitane-14-anisoylate) have been isolated from the roots of Aconitum episcopale. The structures of the new compounds were established by spectroscopic methods and reduction of liaconitine A to the known alkaloid, crassicauline A. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.