Two new alkaloids, haplotubinone (3) and haplotubine (4), were isolated from the aerial parts of Haplophyllum tuberculatum together with the known ligand diphyllin. The structures off the new alkaloids were established by spectroscopic methods in conjunction with X-ray crystallographic analysis of 3. In addition, the amide N-(2-phenylethyl)-benzamide has been identified in this source for the first time. (C) 2001 Elsevier Science Ltd. All rights reserved.