A study on the bioactive principles of Hedyotis diffusa Willd., led to the isolation of a new acyl flavonol di-glycoside which was characterized as kaempferol 3-O[2"-O-(E-6'"-O-feruloyl)-beta-D-glucopyranosyl]-beta-D-galactop yranoside by spectral and chemical methods from the methanolic extract. In addition, three known flavonol glycosides and six known iridoid glycosides were also obtained. The above-mentioned glycosides were tested for antioxidant effects on xanthine oxidase inhibition, xanthine-xanthine oxidase cytochrome c and TBA-MDA systems.