The gastric emptying study using Tc-99m triethylene tetramine polystyrene resin with or without metoclopramide hydrochloride was used in six patients with different disease entities: achalasia, gastric lymphoma, primary amyloidosis, Zollinger-Ellison syndrome, duodenal diverticulum, and short bowel syndrome. All patients had abnormally prolonged gastric emptying times. The patient with gastric lymphoma and the patient with Zollinger-Ellison syndrome had virtually no effect from metoclopramide. The patient with a duodenal diverticulum and the patient with short bowel syndrome had partial and good response to metoclopramide, respectively. Endoscopic and/or autopsy examinations in patients with achalasia, Zollinger-Ellison syndrome, primary amyloidosis, and duodenal diverticulum proved the patency of the pyloric canal. The patient with gastric lymphoma had a mass associated with marked pyloric narrowing and lymphoma cell infiltration of the gastric wall, to explain the abnormal gastric emptying. The gastric emptying study with or without metoclopramide may be used noninvasively to measure gastric function, to determine the nature of gastric outlet obstruction, and to evaluate therapy with metoclopramide.