The achievements of modern domestic pharmacy clearly prove the prospects of searching for biologically active molecules among 1,2,4-triazole derivatives. The aim of our work was to predict the safest compound, select it and unambiguously prove the structure of a new promising molecule, to investigate some parameters of its toxicity. Materials and methods. X-ray diffraction analysis was performed in the laboratory of the Institute of Single Crystals of the National Academy of Sciences of Ukraine (Kharkiv). Computer methods were used to build “structure – toxicity” models and predict LD50 using already created models GUSAR, TEST. The degree of toxicity (DL50) and the approximate doses for the subacute experiment were determined by studying the acute toxicity of the test chemical and the injectable solution based on it. Determination of acute toxicity parameters by intragastric administration was performed on white rats, aged 3-4 months, body weight 200-220 g. Results. Due to the study of the toxicity of 1,2,4-triazole derivatives by non-experimental methods using GUSAR and TEST models, it was found that the test compounds could be classified as low-toxic substances. The compound is an organic salt that exists in the crystal as a solvate with one molecule of methanol and two molecules of water. When studying the structure of the crystal, it was found that the crystal is in the pinacoidal triclinic syngony. According to the results of the studies, it was found that after a single intragastric administration of the compound in doses of 1000, 3000 and 5000 mg / kg, all animals remained alive for 14 days. The basis of the biological action of chemical compounds is the violation of several biochemical processes. We found that the studied blood constants, on the background of the use of newly synthesized substance, underwent some changes. Conclusions. According to the assessment of the toxicity of the drug “VPK-434” when administered intragastrically to laboratory rats, it was found that in accordance with SOU 85.2-37-736: 2011 the test substance belongs to the IV class of toxicity (low toxicity). It was found that the average lethal dose of DL50 of the test substance by intramuscular administration to rats is 1666.66 mg / kg body weight. It was studied that some abnormalities in the hematopoietic system (increase in the number of leukocytes, including eosinophils), liver and kidney function (increased activity of transaminases, decreased serum concentrations of total protein, urea and creatinine) and changes in mineral metabolism of experimental animals groups, on the background of receiving 10 multiple doses of the study drug, was short-term, and the restoration of the functional state of the body of rats could be said as early as 4-5 days after discontinuation of the drug into their body