With the use of the radionuclide gastric-emptying test and a new data processing method, the contraction characteristics of the stomach were analyzed. After ingestion of a radiolabeled test meal, dynamic images of the stomach were acquired and analyzed to determine the frequency, amplitude, and rate of gastric contractions in healthy subjects. The frequency of antral contractions was found to be inversely related with food retention in the stomach; in contrast, the amplitude of the contractions decreased progressively during the course of gastric emptying. The peaks of both antral contraction and filling rate and the time of their occurrence remained constant throughout gastric emptying. The observed patterns of phase distribution and sequential phase changes of the food in the stomach confirmed noninvasively what was already known from invasive technique, i.e., that the proximal stomach does not undergo phasic contractions and that, in the distal stomach, smooth muscle contraction originates in midcorpus and propagates aborally to the pylorus. The scintigraphic test can be used to noninvasively and quantitatively characterize gastric motor function and to delineate the spatial sequence of gastric contractions. This technique can be applied to study the pathophysiology of gastric emptying in various motor disorders.