Procedures have been developed for the determination of the type and location of sugar units present in anthocyanins and other flavonoid glycosides. These procedures are based on standard chemical reactions and have been adapted to a microscale using paper chromatography. Individual flavonoids were found to respond variably to enzymic and chemical hydrolyses, which therefore yield information of limited use only. On the other hand, controlled oxidation has been shown to provide information on the type and position of sugar units attached to the flavonoid nucleus. Degradation using peroxide releases the sugars at the 3-position ; permanganate treatment releases sugars attached to readily ruptured cyclic systems ; and ozonolysis releases sugars attached to phenolic and enolic hydroxyl groups. These three techniques, when used together, can result in the absolute identification of anthocyanins and most other flavonoid glycosides.