Two hundred and fourteen patients with Crohn's disease (CD) were observed for a mean of 9 years. Colonic CD was diagnosed in 25%, small-bowel CD in 17.5%, and ileocolic CD in 57% of the patients. The cumulative operation rates at 10 years were 47%, 58%, and 71%, respectively. Patients with isolated colonic CD were operated on later in the course of their illness than others (p less than 0.05 at 10 years). More than 50% of the patients remained in the 'well being' group regardless of the duration and localization of the disease. The quality of life was better in the non-operated than in the operated group of patients (p less than 0.02). Large-bowel carcinomas occurred in three patients. Of six deaths related to CD, two were caused by cancer and three by renal failure due to amyloidosis. The total number of deaths was 3.6 times that expected.