The effect of small intravenous doses (0.025 and 0.05 mg) of glucagon was evaluated in 22 patients. All 12 patients given 0.05 mg demonstrated by hypotonicity of the stomach and duodenum at 1 min and beginning return of peristalsis at 2 1/2 min. Subsequently, 100 patients with radiographically normal upper gastrointestinal examinations who received 0.05 mg of glucagon intravenously were compared to 100 patients with normal examinations without it. Comparison was made to determine the effect of glucagon on gastric mucosal coating and distention of the stomach and duodenum. In all areas of the stomach, mucosal coating was significantly improved in the glucagon group. There was also increased distention of the distal antrum, duodenal bulb, and duodenal loop. No adverse effects were reported. Because of the short duration of action of glucagon, the examination needs to be coordinated and done rapidly. The routine use of a small dose of glucagon increased the performance time slightly with small additional cost but was compensated for by the increased diagnostic quality of the examination.