Two new diterpenoid alkaloids, subcumine (1) and subcusine (2), were isolated from the roots of Aconitum japonicum Thunb. The structures of these alkaloids were determined on the basis of spectral data, chemical evidence, and X-ray analysis. We also have isolated two known alkaloids, ezochasmaconitine (4) and anisoezochasmaconitine (4). © 1988.