A novel prenylated arylnaphthalene lignan, 7-O-(3-methyl-2-butenyl)isodaurinol, was isolated from Haplophyllum myrtifolium and identified on the basis of detailed spectral analyses, including 2D-NMR spectrometry. The known furoquinoline alkaloids, dictamnine, robustine, gamma-fagarine and skimmianine, the aryltetralin lignan (-)-1beta-polygamain and the flavone chrysosplenetin were isolated from the same source.