An epidemiological study of Crohn’s disease has been carried out in northeast Scotland during the years 1955 to 1969. There were 166 cases during this 15-year period; in 80% the small bowel was the principal site of the disease. Females outnumbered males by nearly 2:1. The risk of developing the disease is greatest in the third decade of life. The annual incidence has increased; in Scotland most of the increase is attributed to colonic disease in older females. Marital status, social class, and familial factors were not important in determining the incidence of Crohn’s disease. Place of residence was important, city dwellers being more often affected and the condition being uncommon in males from rural areas.