The Leyton Obsessional Inventory was administered to 69 orthopaedic patients in Glasgow, and their responses were compared with those of 77 similar subjects in London and 73 in Cork. The responses of the Scots and the English did not differ, but both of these groups were significantly less obsessional than the Irish subjects, who were particularly likely to regard cleanliness and tidiness as virtues in themselves. Obsessionality was unrelated to age, sex, social class, family size and birth order, but higher Leyton scores were found among bachelors, and among women living in the country and without outside employment. It is suggested that the common factor among these 3 subgroups is emotional or geographic isolation, and that this may enhance any tendency to obsessional ruminations and routines. This could also account for the higher Leyton scores and greater incidence of obsessional neurosis in the Irish.