Gastroesophageal scintigraphy is a quantitative technique that can be employed to detect and quantitate gastroesophageal reflux before and after the application of therapeutic modalities, including change in body position, bethanechol, atropine, antacids, and antacid-alginate compounds. Five groups of 10-15 patients each were studied before and after using each therapeutic modality and before and after atropine. The results were compared to the patient's symptomatology and to the acid reflux test. Gastroesophageal scintigraphy was performed following oral administration of 300 microCi 99mTc-sulfur colloid in 300 ml acidified orange juice. Thirty-second gamma camera images were obtained as the gastroesophageal gradient was increased from approximately 10 to 35 mm Hg at 5 mm Hg increments using an inflatable abdominal binder. Data were processed using a digital computer. Reflux was reduced by change in position from recumbent to upright, and by the use of subcutaneous bethanechol, oral antacid, or oral antacidalginate compound. Atropine increased reflux. Gastroesophageal scintigraphy is more sensitive than fluoroscopy, correlates well with clinical symptomatology, and is a reliable and convenient technique for the quantitative estimation of reflux before and after therapy.