The radioisotopic measurement of gastric emptying offers information about an aspect of gastric motility. A procedure performed in our laboratory is presented. It is based on the ingestion of 500 ml saline including 1 mCi (3.7 MBq)113m In-DTPA or 99Tc-DTPA. The subject is placed in a half-supine position. Radioactive counts of the tracer are collected with a gammacamera and processed with a microcomputer, using a special program. This offers the histograms of the whole stomach and of the regions of interest (proximal and distal stomach), and also the half-time of these curves. Normal values range between 8-25 min for each curve half-time. The method has applications in physiology, pharmacology and clinical diagnosis.