Piperazin-2-one and quinoxalin-2-one derivatives are known to possess strong analgesic, anti-inflammatory and spasmolytic activities. An ester condensation between 3,5-diacetyl-2,6-dimethylpyridine and an excess of diethyl oxalate was used for the preparation of 4,4-(2,6-dimethylpyridine-3,5-diyl)bis(2-hydroxy-4-oxobut-2-enoate). The synthesized hydroxyester was shown to readily react with o-phenylenediamine and o-aminophenol with the formation of bis(3,4-dihydroquinoxalin-2 (1H)-one) and bis(3,4-dihydro-2H-1,4-benzoxazin-2-one) derivatives. Compounds were obtained as bright-yellow and orange crystals, sparingly soluble in organic solvents. The structures of the synthesized compounds were confirmed by elemental analysis, IR and NMR spectroscopy. Taking into account the previously published data about the analgesic activity of quinoxalin-2(1H)-one derivatives, we performed biological testing with compounds bis(3,4-dihydroquinoxalin-2(1H)-one) and bis(3,4-dihydro-2H-1,4benzoxazin-2-one). Study of analgesic activity was based on a well-known pain model -acetic acid-induced writhing test in laboratory mice. The analgesic effect was evaluated by the reduction in the number of convulsions (writhings) as a percentage relative to control animals. Study of analgesic activity was performed on mice by recording the specific pain reaction of writhing, caused by intraperitoneal injection of 0.75% acetic acid (0.1 ml per 10 g body weight). Number of writhings for each animal was counted during the subsequent 15 min (using groups of 5 animals). The studied compounds were introduced in the amount of 100 mg per kg as a suspension in drinking water into the stomach by using a feeding tube at 30 min prior to the injection of acetic acid. Reference drug was metamizole sodium, which was introduced by analogous scheme in the amount of 100 mg per kg. Control animals received analogous volume of drinking water. The screening results for compounds with regard to the analgesic activity are presented in Table . Compound bis(3,4dihydroquinoxalin-2(1H)-one) caused a 31.5% reduction in the number of writhings, exceeding by 1.6 times the effectiveness of the reference drug (metamizole sodium), which reduced the number of writhings by only 19.4%. Compound bis(3,4-dihydro-2H-1,4-benzoxazin-2-one) reduced the number of writhings by 19.7%, which was comparable to metamizole sodium. Thus, biological testing revealed that the synthesized compounds in some cases had stronger analgesic activity than the reference drug, metamizole sodium.