After more than a decade of intensive work, the Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) has been finalized and published by the World Health Organization (WHO). It has been produced as a response to recent changes in health service systems in different parts of the world incorporating significant new knowledge that has become available in the past decade. The ICD-10 consists of 21 chapters covering the whole of medical practice. Chapter V of the ICD-10 deals with mental and behavioural disorders and has been produced in several versions, each of which is intended for a particular purpose and aimed at specific users. The main versions of the ICD-10 Classification of Mental and Behavioural Disorders are: Clinical Descriptions and Diagnostic Guidelines (CDDG) – an assembly of detailed specifications of the main clinical features of mental and behavioural disorders intended for general clinical, educational and service use by psychiatrists and other mental health professionals; Diagnostic Criteria for Research (DCR) – a set of specified, operational criteria and rules intended for diagnostic purposes in research on mental and behavioural disorders; Multiaxial Presentations of the ICD-10 – classificatory systems for the assessment of different attributes of the patient's clinical condition, designed for use in adult psychiatry and child and adolescent psychiatry; ICD-10 Primary Health Care Version (ICD-10 PHC) – a simplified list of psychiatric conditions accompanied by guidelines about diagnosis and management for use in primary health care.