The choice of therapy--whether medical or surgical--for patients with gastroesophageal reflux (GER) is often a subject of debate. After a period in which surgery was almost the exclusive mode of treatment in patients with severe complications resulting from GER or in patients who did not respond to medical therapy, long-term follow-up showed that in 20 cases of GER in which only medical treatment was given, a progressive shortening of the esophagus--frequently in the absence of esophagitis--had developed. To investigate the pathophysiology of acquired short esophagus, we studied 34 patients--20 from the initial group and 14 who already had this condition. Clinical assessment consisted of interview, radiologic examination of the upper digestive tract, endoscopic and histologic examinations, and 24-hour home esophagogastric pH monitoring. We noted that acid GER causes shortening in the presence of severe mucosal lesions, while "nonacid" GER--a combination of gastric, pancreatic, and hepatic secretions--causes shortening of the esophagus even without evident mucosal lesions. Symptom evaluation, acid GER pH recording, and endoscopy are not sufficient for determination of the current choice of therapy. It is also important to quantify GER that results from the mixing of gastric and biliopancreatic secretions with use of the esophagogastric pH recording. This should reduce the possibility of silent shortening of the esophagus.