This is a pocket-book version of the new international psychiatric classification produced by the World Health Organisations (WHO), Geneva. Chapter V of the 10th version of "The International Classification of Diseases" (ICD-10). This guide is designed to be an inexpensive, quick and accessible reference to the WHO compiled classification system (ICD-10) for psychiatric and behavioural disorders. It brings together the Glossary with the Diagnostic Criteria for Research and diagnostic notes extrapolated from the Diagnostic Criteria. The new classification will appeal to many user types - clinical psychiatrists in training and practice, researchers, medical records clerks and administrators. Classification of diagnosis in psychiatry is based on the patient's clinical history and observed behaviour pattern. At present there are two classification systems used worldwide: ICD (WHO, Geneva) and DSM (American Psychiatric Association, USA). Both systems are presently being revised.