Objective. To determine the effectiveness and introduce the Poisoning Severity Score (PSS) scale into the clinical practice of the department for patients with acute poisoning with psychoactive substances.Materials and methods. A single–center retrospective and prospective randomized clinical trial was conducted in 200 patients with acute poisoning with the psychostimulant alpha-pyrrolidinopentiophenone and the synthetic cannabinoid MDMB–FUBINACA. To assess the severity of substance poisoning, the Poisoning Severity Score (PSS) scale developed by the European Association of Clinical Toxicologists IPCS/EC/EAPCCT was used.Results and discussion. This scale allows to objectify clinical and laboratory manifestations of acute poisoning with psychodisleptics, to identify the leading syndromes, to predict the risk of complications and emergency conditions.Conclusion. The PSS scale is easy to use and does not require a wide range of diagnostic capabilities from a medical institution, helps to determine the tactics of patient management and determines the volume of emergency care at the hospital stage.