Neuropharmacological properties of LK-998 (3,4,5-trimethoxy-N'-(2,2,6,6-tetramethylpiperidin-4-yliden)benzohydrazide), a 2,2,6,6-tetramethylpiperidone de- rivative have been studied. LK-998 exhibited anxiolytic activity in doses of 10 and 20 mg/kg, significantly increasing the duration of animal staying of in open arms of the elevated plus maze as well as the number of arm entries. The efficiency of drug tested in a dose of 10 mg/kg was comparable with that of afobazole in a dose of 5 mg/kg. In marble burying test, it was also found that animals treated with LK-998 at 10 mg/kg buried a close number of balls to that as rodents treated with afobazole at 5 mg/kg. At the same time, LK-998 in doses 10 and 20 mg/kg did not produce any antidepressant action in the learned helplessness test. Thus, LK-998 in a dose of 10 mg/kg has anxiolytic and anticompulsive effects comparable to those of afobazole at a dose of 5 mg/kg. The study of potenti- al side effects of LK- 998 in a dose of 200 mg/kg (i.e., 20 times the therapeutic dose of 10 mg/kg) showed that the drug tested caused neither side effects nor symptoms of neurological deficiency within 24 hours and on longer terms (4, 10 and 14 days after administration).