Twenty water-soluble mucilages obtained from plants in the Liliaceae, Amaryllidaceae, Dioscoreaceae, Orchidaceae, Saxifragaceae, Malvaceae and Plantaginaceae families were tested for the hypoglycemic activity on administration to normal mice. Considerable activity was observed for most of the mucilages isolated from plants in the Malvaceae family. They have the repeating structure (1→4)-[O-β-(D-glucopyranosyluronic acid)-(1→3)]-O-α-(D-galactopyranosyluronic acid)-(1→2)-O-α-L-rhamnopyranose in their main parts. The deacetylated product of Plantago-mucilages A, the main mucilage present in the seed of Plantago asiatica, also showed remarkable hypoglycemic activity. 1 Antidiabetes drugs. Part 25. Also Part 115 on the validity of the Oriental medicines.