Four new hetisine-type C-20-diterpenoid alkaloids, named as coreanines A-D (1-4), were isolated from the roots of Aconitum coreanum, together with thirteen known alkaloids (5-17). Their structures were elucidated by extensive spectroscopic methods including IR, HR-ESI-MS and NMR techniques. All the isolated compounds were screened for the acetylcholinesterase (AChE) inhibitory effects, and none of them showed considerable inhibitory activity.