We report a 45-year-old woman with chronic peptic ulcer disease and multiple episodes of bowel obstruction, who was admitted with gastric outlet obstruction. Because of gastric hypersecretion, a diagnosis of Zollinger-Ellison syndrome was suspected and an initial serum gastrin of 1,251 pg/ml supported this diagnosis. Subsequent evaluation failed to reveal a gastrinoma. A repeat serum gastrin level after 14 days of continuous nasogastric decompression was 43 pg/ml, suggesting that the initial hypergastrinemia was due to antral distention. It is important to consider the possibility of gastric outlet obstruction as a stimulus for serum gastrins in the range previously considered diagnostic for the Zollinger-Ellison syndrome.