Six new alkaloids, cephalezomines A-F (1-6), have been isolated together with known related alkaloids 7-16 from the leaves of Cephalotaxus harringtonia var. nana and the structures were elucidated by spectroscopic data and chemical methods. Cephalezomines A-F (1-6) showed potent cytotoxicity against tumor cells. (C) 2000 Elsevier Science Ltd. All rights reserved.