The aerial parts of Delphinium siwanense var. leptogen yielded two new norditerpenoid alkaloids siwanine E and siwanine F. Their structures were elucidated as 2,3-dehydro-16-acetylelasine and 2,3-dehydrodictyocarpine, respectively, on the basis of spectral methods including 1D and 2D NM R experiments.