The suitability of a radiopharmaceutical for measuring gastric emptying time of solid meal is described. The gastric emptying T1/2 value of solid meal in normal individuals has been established. Both animal and human experiments indicate 99mTc-DTPA to be an ideal nonabsorbable marker for determing gastric emptying rate and for other gastrointestinal studies as well. Studies are now underway to determine gastric emptying time in patients with gastrectomy and gastrojejunostomy, vagotomy, pyloroplasty, etc.