Inflammatory bowel disease in Iceland during a 30-year period, 1950-1979.

Thirty-three patients with Crohn's disease (CD) and 318 with ulcerative colitis (UC) were identified among the 250,000 inhabitants of Iceland over a 30-year period. The present incidence of CD is 0.9/10(5)/year and of UC 7.4/10(5)/year.