A new piperidine alkaloid, microcosamine C (1), and one known compound, microcosamine A (2) were isolated from the leaves of Microcos paniculata. Structure elucidation was carried out using HR-ESI-MS, 1D and 2D NMR spectroscopic methods and by comparison with data reported in the literature. The absolute configuration at the C-3 hydroxy group of 1 was established by a Mosher esterification procedure. Both the isolates (1–2) were evaluated for cytotoxicity against four selected tumour cell lines and showed only weak activity against RAW 264.7 cell line. © 2016 Informa UK Limited, trading as Taylor & Francis Group.