SUMMARY This study gives detailed information on the two principal groups of patients undergoing excisional surgery with a permanent artificial stoma for Crohn's disease of the large bowel. During the years 1952-71, 64 patients were treated by total proctocolectomy aQdileostomy and 26 patients by excision of the distal large bowel and colostomy.In the group of patients undergoing proctocolectomy, there were two postoperative and six late deaths. Of the 56 patients alive at the end of the follow-up period (average length of follow-up 8.1 years), four had shown evidence of recurrent disease. In each case this occurred following a staged proctocolectomy and at, or immediately proximal to, the ileostomy: the shortest interval between surgery and recurrence was just under 10 years.Among the patients treated by excision of the distal large bowel, there were two unrelated late deaths: with an average duration of follow up of 7.3 years, recurrent disease occurred in only one of the 24 patients alive at the concluding date for this study.The essential diagnostic features of large bowel Crohn's disease have been delineated in a number of studies from this hospital (Lockhart-Mummery and Morson, 1960, 1964;Morson, and Dawson, 1972) and, using these criteria, the surgery undertaken in 84 cases was described (Jones, Lennard-Jones, and Lockhart-Mummery, 1966). The intention in the present paper is to present the results of surgery in the two main groups of patients undergoing excisional operations with the establishment of a permanent artificial stoma. These operations are total proctocolectomy and ileostomy (carried out for diffuse or extensive disease) and excision of the distal large bowel with a terminal colostomy (undertaken for disease apparently confined to the sigmoid colon and rectum). The study includes patients treated by these operations mentioned in the earlier paper and is an elaboration of the results already published in brief by Lockhart-Mummery (1972).The criteria which have been applied for the selection of patients for this enquiry are as follows.(1) Patients have been included if (a) laparotomy only, (b) appendicectomy, (c) (a)