Delayed gastric emptying of liquids and/or solids was hypothesized as a mechanism which could increase the volume of gastroduodenal contents and could contribute to the pathogenesis of gastroesophageal reflux. Gastric emptying of an isotope-labeled mixed solid-liquid meal was compared in a study of 20 age-matched gastroesophageal reflux patients and 20 normal subjects whose sex distribution and weight were similar; and also in a study of 100 reflux patients and 26 normals. The 20 GER patients emptied isotope from the stomach at a slower rate than age-matched normals at 30 min (p < 0.10); 60 min (p < 0.05, one-tailed t-test); and 90 min (p < 0.05). Using the range established from 26 normal subjects for percent of isotope remaining in the stomach after 90 min (mean +/- 2 SD), 53% of the 100 reflux patients evaluated were within the "normal" range of the controls; 41% had delayed gastric emptying exceeding the upper limit of isotope retention; and 6% emptied isotope rapidly. The means for LES pressure, age, and weight among the slow and "normal" emptying reflux esophagitis patients were similar. Based on the composition of the test meal, it is hypothesized that motor functions of the stomach may be abnormal in a high percentage (41%) of GER patients. The results also suggest a rationale for employing agents which enhance gastric emptying in the therapeutic approach to gastroesophageal reflux.