TWO new diterpenoid alkaloids, subcumine I and subcosine (?), were ~solated 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 (3) . and anisoezochasmaconitine (4).Recently, we reported an isolation of eighteen alkalo~ds~'~ from Aconitum japonlcum Thunb. In thls paper we report isolation and structure determination of two new Clg-diterpenoid alkaloids, named subcumine 11) and subcusine (t) together 4with known alkaloids, ezochasmacon~tine (!14 and anisoezochasmaconitine (4) . We also report the revised assignments of 13c-chemical shifts of C(9). C(10), and C(13l in the related Clg-diterpeno~d alkaloids.