Synthesis of N-substituted derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones (10-14, 18-21) is described. In the "writhing syndrome" test all compounds studied exhibited potent analgesic activity which was superior than that of acetylsalicylic acid. In the "hot plate" test imides 10, 12, 13, 18-20 acted also stronger than aspirin. Furthermore all compounds tested significantly suppressed the spontaneous locomotor activity of mice and prolonged barbiturate sleep of these animals.