One hundred and four patients were treated by restorative proctocolectomy with ileal reservoir for ulcerative colitis and familial polyposis. Three different designs of reservoir were used (triple loop 68, double loop 13, quadruple loop 23). There were no postoperative deaths but six (5.8 per cent) had the reservoir removed. Rates for pelvic sepsis were 25, 15 and 13 per cent, and for intestinal obstruction requiring laparotomy 14.7,0 and 8.6 per cent. Function was assessed in 88 patients (58, 12 and 18) after mean intervals from closure of the ileostomy of 23.7, 12.7 and 4.5 months. Frequency of defaecation per 24 h was 3.7 +/- 1.6, 5.5 +/- 1.6 and 4.1 +/- 1.3, being significantly greater for double loop reservoirs; night evacuation was more prevalent in the same group (26, 58 and 22 per cent). Significantly fewer patients with triple than with double loop reservoirs required antidiarrhoeal medication (19 and 58 per cent). Normal continence occurred in 67, 75 and 89 per cent of patients in the three groups. All patients with double or quadruple loop reservoirs defaecated spontaneously while only 41 per cent with triple loop reservoirs did so. Mean intra-operative reservoir volumes were 177 +/- 64, 172 +/- 58 and 325 +/- 37 ml and volumes after closure of the ileostomy were 416 +/- 176, 197 +/- 69 and 322 +/- 33 ml respectively. Double loop reservoirs were significantly smaller than the other two designs after ileostomy closure. There was an inverse relationship between reservoir volumes and frequency. A quadruple loop reservoir directly connected to the anal sphincter preserved spontaneous evacuation and resulted in function similar to that obtained with the triple loop reservoir.