Statistical data show that more than 130,000 people in Ukraine are diagnosed with cancer every year. Cancer can affect any organ and eventually the whole body. In most cases, cancer is a tumor affecting epithelial, mucous, muscle, fat, and bone tissues. Also, processes related to malignant formations can occur in the blood and lymph. The main mechanism that triggers the process of formation of neoplasms is a violation of growth and, accordingly, cell division. They begin to grow uncontrollably, multiply, and can also migrate, spreading to nearby tissue structures, and later degenerate into atypical (malignant) ones. Cancer is one of the most life-threatening diseases. Literature data show that more than 90% of cancer patients die due to chronic metastases. Cancer therapy involves the use of drugs that block the growth and spread of cancer cells by affecting certain molecular structures involved in the growth, progression, and spread of cancer. The diversity of the use of means for cancer therapy, namely, hormone therapy, the use of angiogenesis inhibitors and apoptosis inducers, has provided scientists with various options for finding effective means to fight this disease. Heterocyclic compounds are the most common among organic substances. All of them are of natural or synthetic origin and play an extremely important role in human life. A scientifically proven fact today is the high biological activity of 1,2,4-triazole derivatives, they are also used as plasticizers for plastics, anti-corrosion agents, additives to various types of fuels, plant protection agents, etc. Derivatives of 1,2,4-triazole are well known as biologically active compounds, some of them are active substances of medicines. Scientists in many countries of the world are studying the properties of 1,2,4-triazole derivatives. The spectrum of pharmacological activity of 1,2,4-triazoles is wide enough, which allows scientists to choose different directions of research tests. It is also known that 1,2,4-triazole derivatives are low-toxic or practically non-toxic compounds. Studying the toxicity of biologically active molecules is a primary task on the way to their introduction into practical medicine. It was previously established that 5-((5-bromofuran-2-yl)-4-methyl-3-thioheptyl)-1,2,4-triazole has anticancer activity, acting selectively and purposefully on cancer cells. Therefore, it was necessary to investigate the acute toxicity of 5-((5-bromofuran-2-yl)-4-methyl-3-thioheptyl)-1,2,4-triazole by the method of experimental research and using computer technologies. Materials and methods. To achieve this aim, we used both classical and modern methods. Timely well-known methods for computer prediction of acute toxicity GUSAR (Germany), ProTox 3.0 (Germany), TEST (USA) and pkCSM (Australia). To obtain more reliable results, we also used the V. B. Prozorovsky express method in vivo on white nonlinear rats. Results. The data obtained for predicting acute toxicity using all four computer services have similar values. It should also be noted that the experimental results correspond to the obtained non-experimental data. Therefore, the compound 5-((5-bromfuran-2-yl)-4-methyl-3-thioheptil)-1,2,4-triazole can be attributed to the fourth class of toxicity according to the classification of K. K. Sydorov. Conclusions. According to generalized data, the compound 5-((5-bromfuran-2-yl)-4-methyl-3-thioheptil)-1,2,4-triazole has an LD50 value of 1245 mg/kg and is a low-toxic substance.