A prospective randomized trial was carried out to determine whether use of a high-pressure closed-suction intraperitoneal drain was associated with a reduction in morbidity rate after colorectal resection and to examine the influence of drainage on postoperative fluid collections. A consecutive series of 148 patients who underwent colonic or colorectal resection were randomized to receive no drain (n = 51) or a high-pressure closed-suction drain for either 3 (n = 47) or 7 (n = 47) days. Three patients were excluded. All patients underwent abdominal ultrasonography on days 3 and 7 and those undergoing left-sided colorectal resection (n = 96) received a water-soluble contrast enema on day 7. The three groups of patients were similar in age, sex, diagnosis and the numbers of sutured and stapled anastomoses. The presence of a drain did not influence the postoperative morbidity or mortality rate. If the anastomosis leaked, neither faeces nor pus emerged from the drain. Ultrasonographic detection of a fluid collection was of no value: such collections bore no relationship to radiological or clinical leaks or the postoperative course. Routine use of a high-pressure suction drain after colorectal resection appears to be unnecessary.