In the 19th century the triumphs of neuropathology and the clinico-anatomical method led to the evolution of neurology as a separate 'organically' based discipline associated with the concept of functional localisation. At the same time the growth of psychodynamic psychiatry contributed to the progressive separation of the two disciplines, with neuropsychiatry sitting uneasily in the middle. Psychiatrists are now showing increasing interest in the structure and function of the nervous system, but are having difficulty in integrating their findings into 'functional' diseases. This may be because disorder of function in the nervous system is much more complex than previously envisaged. The function of the nervous system is profoundly affected by psychological and social factors. The view that neurology is wholly 'organic' and synonymous with structural disease of the nervous system is fallacious. Neurological patients have complex dynamic disorders of function in the nervous system whether or not structural disease is present.