Smoking has been related to several aspects of personality but the association with neuroticism is rather uncertain (Eysenck, 1965). The Royal College of Physicians (1962), in their first report, Smoking and Health, suggested that smokers tend to be more neurotic. This is supported by the view of the U.S. Public Health Service (1964) that there is a relationship between the smoking habit and a personality configuration which is vaguely described as neurotic. However, in the latest report of the Royal College of Physicians (1971) it is stated that this claim has not been substantiated. Even more recently, Eastwood and Trevelyan (1971) concluded that their study in a random half of those aged 40 to 64 years in a London group practice gave no support to this hypothesis. It therefore seems worth reporting the results of an epidemiological survey in South Wales which was concerned mainly with headache but which included standard questions on smoking habits and also questions designed to give a neurotic grade for each individual. METHODS In 1968 a random sample of 2,000 electors living in the northern half of the Pontypridd constituency in Glamorgan was sent a questionnaire by post. This included questions on headache, current smoking