The author made an organizational and legal, clinical and pharmacological study of the latest International Classification of Diseases (ICD-11) concerning its changes compared to the ICD-10. Particular attention was paid to new ways of marking of disease codes and new functions of the ICD-11. Novel structure based on cluster coding, which was implemented into the new revision was mentioned, which allows to connect the main diagnostic codes with advanced clinical indicators. Author found that for the first time, the new revision has become a fully electronic publication that provides access to more than 17,000 diagnostic categories that contain more than hundred thousand of terms of the medical diagnostic index. The new ICD-11 concept of linearization for the national needs of each country was taken into account, which will save budget expenditures for the future. In the new edition of the ICD-11, for the first time, gambling addiction is classified as a mental disorder – behavioral addiction to online and offline gambling. The list of ICD-11 short stories also includes the classification of the following: chronic pain, burnout, stroke, sexual health, post-traumatic stress disorder, allergies, alternative medicine, etc. It is a more powerful health information system based on a formal ontology, designed to integrate information technology into modern infrastructures. A comparison with the ICD-10 on mental and behavioral disorders due to the use of psychoactive substances was made. The ICD-11 has been identified as having a more comprehensive list of disease diagnosis codes, and in the ICD-10 the section on mental and behavioral disorders due to substance use has eleven core codes. Indicated the prospects of using of the ICD-11 in medical practice.