Abstract
In recent years, concern has been expressed that the use of medicinal drugs, notably those acting upon the central nervous system, may be a causative factor in road accidents. A nationwide programme of research was therefore initiated in England and Wales in late 1985. The results indicate that the overall incidence among all road users of drugs likely to affect the central nervous system was 7.5 per cent, and with the exception of diazepam (1.1 per cent), no single medicinal drug was recorded at a rate greater than about one half per cent.