All 260 patients diagnosed as having Crohn's disease between 1958 and 1973, in the Nottingham area, were sought and demographic and social characteristics obtained by personal interview. These were compared with the general population, using the 1971 census data. We found significantly high proportions of patients who were female; married; in the age groups 20-39 and 60-54; and in managerial or skilled manual occupations.