Aim. To synthesize, prove the structure and study the analgesic and anti-inflammatory activities of 3-(het)-aryl-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitrile derivatives. Results and discussion. Condensation of 2-methoxy-3,4,5,6-tetrahydro-7H-azepine with cyanoacetic acid hydrazide leads to formation of 2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acetonitrile. The latter readily reacts with the corresponding (het)arenecarbaldehydes in refluxing ethanol in the presence of catalytic amount of piperidine yielding a series of new 3-(het)aryl-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitrile derivatives. Further functionalization of 3-(4-hydroxy-3-R-phenyl)-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitriles has been done by modification of the OH group. One of the compounds synthesized, namely 3-(4-hydroxyphenyl)-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitrile, exhibits a high level of the analgesic activity on the “hot plate” model, and a similar level of the activity on the model of “acetic acid-induced writhings” as compared to ketorolac. The results obtained indicate the pronounced antinociceptive activity for the test compound. Experimental part. 1H NMR spectra of the compounds synthesized were recorded on a Bruker VXR-300 spectrometer (Germany) operating at a frequency of 299.945 MHz, in DMSO-d6, using tetramethylsilane (TMS) as an internal standard. Melting points were measured using a RNMK 05 device (VEB Analytik,Dresden). The elemental analysis was performed on a EuroEA 3000 elemental analyzer. The analgesic and anti-inflammatory activities of 3-(4-hydroxyphenyl)-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitrile were determined using models of “carrageenan induced paw edema”, ”hot plate” and “acetic acid-induced writhings”, and compared to the reference drug ketorolac. Conclusions. A series of new 3-(het)aryl-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitrile derivatives can be easily synthesized by the interaction of 2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acetonitrile with (het)arenecarbaldehydes. The hydroxy group in 3-(4-hydroxy-3-R-phenyl)-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitriles can be modified to obtain phenyl esters of aliphatic and aromatic carboxylic acids. The high level of the analgesic activity for 3-(4-hydroxyphenyl)-2-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)acrylonitrile has been determined.