Three new C 19-diterpenoid alkaloids, named aconitramines A (1), B (2), and C (3), were isolated from Aconitum transsectum. By UV, IR, 1D- and 2D-NMR, and MS analyses, their structures were elucidated as 18-methoxyvilmoraconitine, 18-demethoxydolichotine A, and 18- demethoxydolichotine B. Compound 1 is the second known C 19- diterpenoid alkaloid with a three-membered ring formed by C(8), C(9), and C(10). Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich, Switzerland.