From a commercial source of aconitine, "Aconitine Potent Merck", isolated from Aconitum napellus L, Lot No. 30169, a new minor norditerpenoid alkaloid, "merckonine" has been isolated. Structure (1) for the new alkaloid was assigned on the basis of its physical and spectroscopic data and synthesis from aconitine. The known alkaloids 3-deoxyaconitine, aconitine and mesaconitine were also isolated in pure form from this commercial source.