Two new C18-diterpenoid alkaloids, piepunendines A (1) and B (2) were isolated from the roots of Aconitum piepunense. Their structures were established on the basis of spectral data (1H and 13C NMR, 2D NMR, HR ESIMS). Piepunendine B is the first naturally occurring C 18-diterpenoid alkaloid having the 2-(p-hydroxyphenyl)ethoxy group at C-8.