Some new benzenesulfonylthiourea derivatives substituted with pyridazinone (2a–o) were synthesized by refluxing the appropriate 6-aryl-2-(p-sulfamylphenyl)-4,5 dihydropyridazine-3(2H)-ones with isothiocyanate in dry acetone over anhydrous K2CO3. All the synthesized compounds were characterized on the basis of IR, 1 H NMR, 13C NMR, DEPT and MS data, and elemental analysis. These compounds at the dose of 20 mg/kg were tested for blood glucose lowering activity in glucose-fed hyperglycemic normal rats. Five compounds (2a, 2d, 2l, 2m, and 2n) markedly reduced the content of glucose in rat blood (by more than 25%). Compound 2d showed the maximum reduction (38.8%).