Two new iboga-vobasine-type bisindole alkaloids iV-demethylervahanine A (1) and iV-demethylervahanine B (2) and one new chippiine-type alkaloid 3-0-methyl-1O,11-demethoxychippiine (3) were isolated from the roots of Ervatamia cumingiana collected in Thailand. Their chemical structures were determined by spectroscopic analyses. Compounds 1 and 2 are bisindole alkaloids having a linkage between C-3 in the vobasine unit and C-11' or C-10' in the Iboga unit, respectively. © 2019 The Japan Institute of Heterocyclic Chemistry