The aerial parts of Haplophyllum thesioides yielded a new alkaloid, thehaplosine [4,5-dimethoxy-11-methylfuro(2,3-c)acridin-6(15H)-on] and a new coumarin, thesiolen (4-methoxyangelicin) in addition to known alkaloids, kokusaginine, skimmianine, pteleine, nkolbisine, heliparvifoline and flindersine as well as known coumarins, seseline, scaporon and angustifolin. © 1993, Taylor & Francis Group, LLC. All rights reserved.