From the root extracts of Aconitum forrestii Stapf, we have isolated four new alkaloids: acoforine (6), acoforesticine (8), acoforestine (10) and acoforestinine (14), besides crassicauline A, forestine and munaconitine. The structures of these alkaloids were determined on the basis of spectral data and correlation with alkaloids of established structures. The structure and stereochemistry of acoforestine (10) was confirmed by an X-ray crystal structure determination.