Between 1974 and 1987, we performed 18 left colonic interpositions for benign oesophageal disease: caustic lesions in 6 patients, undilatable reflux stenosis in 5, reoperative peptic strictures in 5, penetrating wound in 1 and iatrogenic stricture following oesophagogastric transection for bleeding in 1. Four patients were women. The mean age was 40 +/- 19 years. In 10 patients a left thoracotomy was used; in the other 8 a cervico-abdominal approach was employed. One patient died postoperatively from liver failure. The mean follow-up was 11 +/- 4 years. Clinical results were excellent or good in 12 of the remaining 17 patients (71%). These results varied according to the length of colon interposition; in patients with long colonic interposition, poorer results were achieved. The motor activity of the colonic transplant was evaluated by manometric studies. After intraluminal injection of 30 ml of liquid, the colon responded uniformly with sequential peristaltic waves. Transmission of the oesophageal waves through the oesophagocolic anastomosis was studied in 2 patients. After wet swallows, the oesophageal contractile waves were followed by colonic waves. Solid radionuclide colonic transit studies were carried out in 18 control subjects and in 18 patients with colon interposition. In subjects with a normal oesophagus, the general pattern was rapid emptying of the bolus through the oesophagus. Findings in patients with a short transplant were similar to those observed in normal oesophagi. In most patients with long transplants the transit was abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)