We cloned a uridine-diphosphate dependent glycosyl-transferase RUGT-10 from Oryza sativa. The recombinant enzyme was expressed by glutathione-S transferase gene fusion system in Escherichia coli. RUGT10 showed different regioselectivity depending on the structures of substrates (e.g. flavanone, flavonol, and flavone). Apparently, flavanone such as naringenin and eriodictyol gave one 7-O-glucoside while flavone and flavonol gave more than two products with preferential glucosylation position of hydroxyl group at C-3 position.