The structure of brunonine (1), a new C20-diterpenoid alkaloid isolated from the whole plant of Delphiniumbrunonianum Royle, was established on the basis of spectroscopy and the result of X-ray crystallography. Brunonine (1) was shown to possess the atisine azomethine (4) skeleton, with an ethoxyl group at C(19) position. © 1986.