Cardiff, UK residents [n = 219] were identified with Crohn''s disease between 1934 and 1976, during which period 40 of them died. Young patients diagnosed under the age of 20 yr had a significantly raised standardized mortality ratio ( SMR) which was 11. The risk of death was particularly high during the first 2 1/2 yr after diagnosis and again after the disease was present for more than about 13 yr. Case fatality has not diminished during the last 40 yr despite changes in treatment.