In a questionnaire study of 89 Danish gastroenterologists the current diagnostic strategy in patients suspected of having duodenal ulcer disease was elucidated. A case summary concerning a patient with upper abdominal pain was presented. It was assumed that the patient had had a double-contrast barium meal examination or an upper gastrointestinal endoscopy performed. If the X-ray had revealed a deformity of the duodenal bulb, 30% of the gastroenterologists would offer the patient specific medical treatment (H2-blocking agent etc.), but a significantly higher number of gastroenterologists, 45%, (p less than 0.05) would offer specific medical treatment if a deformity was revealed at endoscopy. There was also a significant difference (p less than 0.01) between those who would offer specific treatment if X-ray (84%) or if endoscopy (100%) had revealed an ulcer. Considerable variation was found among experts in their decisions on the basis of X-ray and endoscopy in patients with suspected duodenal ulcer disease. Gastroenterologists generally rely more on endoscopic than on radiographic findings.