Patients undergoing colorectal surgery who required a defunctioning stoma were randomly allocated to receive either a loop ileostomy (n = 23) or transverse loop colostomy (n = 24). Assessment was made during construction, immediately postoperatively, during the period of outpatient supervision and before and after stoma closure. The ileostomy was associated with significantly less odour than the colostomy (P less than 0.01) and required significantly less appliance changes (P less than 0.05). Furthermore eleven patients (58 per cent) with a colostomy experienced three or more problems with stoma management compared with only three patients (18 per cent) with an ileostomy (P less than 0.05). Wound infection was also significantly more common after closure of the colostomy compared with the ileostomy. Both types of stoma were demonstrated objectively to defunction the distal bowel almost completely. These results indicate that a loop ileostomy is the procedure of first choice when a stoma is needed to defunction the distal colorectum.