A new diterpenoid alkaloid, macroyesoenline (1), and a new norditerpenoid alkaloid, 9-hydroxyvirescenine (2), have been isolated from the roots of Aconitum yesoense var. macroyesoense. Their structures were elucidated on the basis of spectral data (1D- and 2D-NMR experiments) and mass spectrometry. The known norditerpenoid and diterpenoid alkaloids delphinifoline (3) and cochlearenine (13) were isolated for the first time from this plant. © 2009 Verlag Helvetica Chimica Acta AG.