Objective. To study the analgesic and anti-inflammatory activity of water-soluble hydrazine derivatives of 2,4-dioxobutanoic acids, as well as to determine the relationship between the structure of substances and their biological effects. Materials and methods. The laboratory synthesis methods were applied to obtain 2-hydrazine derivatives of 2,4-dioxobutanoic acids. The compounds were tested for biological activity using a hot plate test in mice and an acute inflammatory reaction caused by carrageenan-induced paw edema in rats. Results. The analgesic activity of four compounds is comparable to that of nimesulide. One of the substances obtained is found to exhibit higher anti-inflammatory activity than nimesulide during the 1st and 3rd hours of the experiment. Two compounds with a combination of high analgesic and anti-inflammatory activity were identified. The effect of certain radicals in the structure of the substances on the activities studied was discovered. Conclusions. The revealed relationship between the structure of original compounds and their biological activities can be used in the further synthesis and search for new domestic pharmaceutical substances with investigated effects.