A novel dimeric 3-prenylated coumarin 1 has been isolated from the aerial parts of two species of Rutaceae, Microcybe multiflorus and Nematolepis phebalioides. Compound 1 was identified, on the basis of spectral analysis, as (rel)-(E)-1-(7-hydroxy-8-methoxycoumarin-3-yl)-2-[1,4a-dimethyl-2a-(7-hydroxy-8-methoxycoumarin-3-yl)-cyclohex-1-en-4-yl]-ethene, to which we have assigned the trivial name microcybin. In addition, N. phebalioides yielded the furoquinolines evolitrine, skimmianine, flindersine, and halfordinine, and the pyranocoumarin seselin.