Three new C19-diterpenoid alkaloids, named apetaldine H (1), apetaldine I (2) and apetaldine J (3), were isolated from the root of Aconitum apetalum. Their structures were elucidated by extensive spectroscopic analyses including 1D, 2D NMR, and HR-ESI-MS. Compounds (1-3) were evaluated for their cytotoxicity against the MCF-7, HepG2 and H460 human cancer cell lines. © 2018 The Japan Institute of Heterocyclic Chemistry.