FIELD: organic chemistry, biochemistry. SUBSTANCE: invention relates to novel derivatives of (tetrahydro-1-oxido-thiopyrane-4-yl)phenyloxazolidinone of the general formula (I) 
where R1 means methyl, ethyl, cyclopropyl, dichloromethyl group; R2 and R3 are similar or different and mean hydrogen or fluorine atom, or their pharmaceutically acceptable salts. Invention relates also to novel derivatives of (tetrahydro-1,1-oxido-thiopyrane-4-yl)phenyloxazo- lidinone of the general formula (II) 
where R2 and R3 are similar or different and mean hydrogen or fluorine atom; R4 means ethyl or dichloromethyl group, or to their pharmaceutically acceptable salts. Invention relates to method for testing derivatives of oxazolidinone of the formula (I) or (II) that can show inhibitory effect on monoamine oxidase activity involving the following steps: a) incubation of potential inhibitor with monoamine oxidase in buffer solution with pH value from about 7.0 to 7.5; b) addition of 1-methyl-4-(1-methyl-2-pyrryl)-1,2,3,6-tetrahydropyridine to the above indicated solution; and c) determination of inhibitory effect of the above indicated oxazolidinone on monoamine oxidase activity. Invention provides preparing compounds exhibiting inhibitory activity on monoamine oxidase activity. EFFECT: improved testing method, valuable biochemical properties. 21 cl, 1 tbl, 10 ex
