The influence of anastomotic configuration on recurrence of symptomatic Crohn's disease has been assessed in a sequential study of patients undergoing resection of ileal Crohn's disease. Between 1972 and 1991 92 patients had 102 ileocolonic anastomoses constructed after resection of intestinal Crohn's disease. The configuration of the ileocolonic anastomosis was either end to side (ES, n = 68) or side to side (SS, n = 34). The majority of patients in both groups were female and both groups were similar for duration of Crohn's disease at resection, steroid therapy, previous number of intestinal resections, indication for surgery and length of ileum resected at operation. No anastomotic leak occurred in either group. A total of 39 patients developed symptomatic recurrent Crohn's disease including 31 (46%) in the ES group and 8 (24%) in the SS group. This difference was related to the length of follow-up, the annual rate of symptomatic recurrence was almost identical for both end to side (0.066) and side to side (0.052) anastomoses.