4-{[(2E)-5-hydr-oxy-3,7-dimethylocta-2,6-dien-1-yl]-oxy}-7H-furo[3,2-g][1]benzopyran-7-one), C(21)H(22)O(5), is a known furan-ocoumarin, which was isolated from the Chinese herbal product Radix seu Rhizoma Notopterygii. The crystal structure shows a weak O-H⋯O hydrogen bond.