The course of all 113 patients with Crohn's disease whose initial procedure involved an anastomosis operated upon from 1942 to 1972 was followed through 1980. The calculated cumulative 30-year total mortality was 23.4%, 16.7% disease-related. The cumulative recurrence rate was 29% at five years, 52% at ten years, 64% at 15 years and 84% at 25 years, with no important differences between disease locations and types of operation. Sex, age, duration, granulomas, enteral or perirectal fistulas and length of the resection, the disease, and the proximal resection margin had no significant influence on the rates of development of recurrent disease or on functional outcome. By far the most common site of recurrence was the neo-terminal ileum, but in ileocolitis compared with ileitis, recurrence was 5.2 times more likely (p = 0.0001) to involve the adjacent or remote colon as well. Moreover, only 1/63 ileitis patients eventually required ileostomy, whereas 15/47 patients with ileocolitis or colitis ultimately required this procedure (p less than 0.001). The current status of the patients was excellent or good in 64% and unwell or dead related in 24%. Urolithiasis developed in 19%.