Diplolaena mollis P. G. Wilson (Rutaceae, Boronieae) is a species restricted to the south of Western Australia, with no previous phytochemical studies reported. Dried powdered twigs (160 g) of D. mollis were Soxhlet-extracted sequentially with petroleum ether (bp 40–60 °C), CH₂Cl₂ and MeOH. The petroleum ether and CH₂Cl₂ extracts were subjected to column chromatography on silica gel and purified by preparative TLC, resulting in the isolation of five coumarins: xanthoxyletin, alloxanthoxyletin, dipetalolactone, umbelliferone, and pimpinellin. The presence of coumarins in D. mollis is consistent with the genus' placement in the Boronieae tribe (which includes coumarin-producing genera like Phebalium, Chorilaena, Eriostemon, and Philotheca), and the distribution of 5,7-dioxygenated pyranocoumarins in Boronieae has chemotaxonomic significance.