Enterogastric reflux was studied using the scintigraphic method in 20 patients with colonic interposition for benign esophageal disease. The state of the transplanted colonic mucosa was evaluated by endoscopy. In 16 patients, reflux of the duodenal contents into the stomach could be seen. In eight, reflux of the duodenal contents into the interposed colon could be demonstrated. There were no differences in the occurrence of reflux into the colonic graft between the isoperistaltic and antiperistaltic interpositions. In three patients, signs of colitis on the mucosa on the lower part of the graft were observed by endoscopy. Each of these patients had a reflux of the duodenal contents into the colonic graft. In monitoring the 24 hour pH of these three patients, one patient had marked acid reflux. Alkaline reflux was not observed. It is concluded that enterogastric refluxis frequent in patients with colonic interposition. Its role in the development of lower colonic graft colitis change is discussed.