Recently several cases have drawn our attention to problems associated with professional driving and mental disorder. All drivers are responsible for informing the licensing authority of any disability likely to cause them to drive hazardously. Medical Aspects of Fitness to Drive (Raffle (ed.), 1985) gives detailed guidelines to help doctors advise their patients. Those relating to ordinary licence holders appear intuitively correct and most psychiatrists would give similar advice without reading them. However, the guidelines for vocational drivers, especially holders of Public Service Vehicle (PSV) and Heavy Goods Vehicle (HGV) licenses, are more stringent because of the serious consequences when accidents occur. The guidelines follow those of the Royal College of Psychiatrists, revised in 1983.