Disorders of gastric emptying are being increasingly recognized as the basis for "functional" symptoms in the general population. Recent research suggests that abnormal gastric emptying may also be the cause of common gastrointestinal problems in those with cancer, and can be a complication both of the disease and of its treatment. These disorders are diagnosed by measuring the rate of gastric emptying and comparing it with the normal rate. There are numerous methods of measurement available, each with inherent advantages and disadvantages. Differences in method application and a lack of standardization limit the extent to which results from different institutions can be compared. Because of the limitations of existing methods, new technology is frequently being evaluated. Radionuclide measurement is the current method of choice.