AbstractColonoscopic biopsies were performed on 38 patients, 10–13 years after jejuno‐ileal bypass. No significant dysplasia or premalignant change was seen in 371 biopsies. In one patient two tubulovillous adenomata were found in an otherwise normal colon, which is likely to be a chance finding. Although it will take another 10–20 years to establish whether jejuno‐ileal bypass is associated with an increased risk of large bowel cancer in humans, there is at present no indication for regular colonoscopic surve