A phytochemical investigation on the stems of Glycosmis puberula var. craibii led to the isolation of a new indole alkaloid (named glycosmiscrol A, 1), together with four known compounds (2–5). The new structure was elucidated by detailed analysis of comprehensive spectroscopic methods. All isolated compounds were evaluated for their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1–5 showed significant antiproliferative effects with IC50 values ranging from 0.16 to 8.58 µM. © 2020 Informa UK Limited, trading as Taylor & Francis Group.