In an attempt to estimate the incidence and severity of the functional and mechanical problems associated with colon interposition for benign oesophageal disease, a retrospective analysis of a single centre experience was undertaken.Between 1961 and 1990, a total of 365 patients who survived the postoperative stay in hospital were followed up over 7-38 years and form the basis for this study. Upper gastro intestinal symptoms in these patients were investigated clinically, radiologically, endoscopically and in the oesophageal laboratory. Mechanical and functional abnormalities requiring surgical intervention for relief of symptoms were documented.There were two late presentations of colo bronchial fistulae, two instances of persistent colo cutaneous fistulae, three cases of diaphragmatic herniation and two adenocarcinomata of the colo gastric junction in the patients with short segment colon interposition. Amongst the long segment colon interposition patients there was one hiatal obstruction, two thoracic inlet delays associated with pseudo diverticulosis and one hiatal obstruction. One other patient presented with an adenocarcinoma of the intrathoracic colon. There were four patients requiring revision of the cervical oesophago colic anastomosis, two of them on recurrent occasions. The remaining sequelae were functional and were associated with increasing redundancy of the colonic segments at different levels. There were 17 such patients, two of whom developed significant redundancy at two different levels.Although the patients with short segment colon interposition developed predominantly avoidable iatrogenic complications, those undergoing long segment colon interposition developed functional sequelae requiring re-operations in later life.