3, 4-Dihydro-3-oxo-2H-1, 2, 4-benzothiadiazine-1, 1-dioxides were synthesized as conformationally rigid analogues of sulfonylurea hypoglycemic agents. All the compounds prepared showed hyperglycemic activity. The hyperglycemic activity was enhanced for the diabetic rats in which the blood glucose level was increased by 30-70%.