Three new diterpenoid alkaloids, designated naviconine (1), naviculine (2) and naviconitine (3), together with five known diterpenoid alkaloids (4)-(8) were isolated from the whole plant of Delphinium naviculare var. lasiocarpum W. T. Wang. The structures of the new compounds were established on the basis of spectroscopic analyses including HR-ESI-MS, 1D and 2D NMR analyses. All of the compounds were evaluated in vitro for cytotoxicity against HT-29, MDA-MB-231 and HeLa cancer cell lines using the MTT method.