Two new C-20-diterpenoid alkaloids, named aconicarchamines A and B (1 and 2, resp.), were isolated from Aconitum carmichaelii. By UV, IR, MS, and 1D- and 2D-NMR analyses, their structures were elucidated as 14,17-dihydro-14,17-dihydroxyajabicine and 15-O-acetyllassiocarpine. Compound 1 is the third C-20-diterpenoid alkaloid with the lycoctine skeleton bearing an exocyclic C-atom at C(14).