The application of new radioisotope methods in external in vivo scanning has increased our knowledge of how disease and treatment can effect gastric emptying (GE). Solids leave the stomach more slowly than liquids, and conditions causing gastroparesis affect solids before liquids. Gastric mucosal abnormalities and their treatment can affect GE. Diseases of the gastric musculature, including the inflammatory and endocrine myopathies, muscular dystrophies, and infiltrative disorders, can result in significant gastroparesis. Acute and chronic neuropathy may both affect gastric emptying. The latter neuropathies are now the subject of intense investigation with new prokinetic drugs. Finally, abnormal GE may be a major clinical feature of certain severe psychiatric disorders.