Chemical investigation of the roots of Gelsemium elegans collected in Thailand resulted in the isolation of the new indole alkaloids, 16-epi-voacarpine, 19-hydroxydihydrogelsevirine, and 19-(Z)-taberpsychine, along with eight known bases. Among them, the structure of "akuammidine" and koumidine were revised to have 19-(Z) ethylidene configuration. From the seeds of G. elegans 14-hydroxygelsedine was obtained. Furthermore, three new alkaloids, koumine N-oxide, gelsemine N-oxide, and 19-oxo-gelsenicine, were found from the leaves of G. elegans. A new and plausible biogenetic route of gelsemium alkaloids is proposed. © 1988.