The root ofA. septentrionaleKoelle has been found to contain a number of alkaloids, seven of which have been isolated and characterized. The major alkaloid is the previously known lappaconitine. The minor bases, except alkaloid D, appear to be new. Of these, the main one, alkaloid A (C43H59O12N3), is a double ester, since it consists of an alkamine esterified with a methyl ester ofN-succinoylanthranilic acid. The other minor bases are alkaloid B (C17H25O2N), alkaloid C (C19H27O3N), alkaloid D (C30H42O7N2) which is deacetyllappaconitine, alkaloid E (C37H54O7N) containing no ester group, and alkaloid F (C19H29O6N). No trace of the previously reported cynoctonine and septentrionaline was found.