In June 2018, WHO published the 11th edition of the International Classification of Diseases (ICD). The new edition introduced numerous changes. One of the most important was to rebuild the coding system and adapt ICD to digital use. A reconstruction of the coding system enabled more comprehensive alphanumeric coding of complex clinical situations by the introduction of cluster coding. The chapter on mental disorders has also changed. ICD-11 has been updated to take into account the results of international expert cooperation and new information on mental disorders. Many of the secondary clinical categories have been moved higher in the hierarchy that created new subchapters. Many categories have been moved to other subchapters. Taking into account the modern epidemiology and knowledge about the etiology of mental disorders, some categories have been removed from ICD. Moreover, several nonexistent categories have been added. The article summarizes and discusses the most important changes in ICD with the introduction of ICD-11, both in the coding system and in individual subchapters covering mental health issues.