The mechanism of gastric stasis in disorders of gastrointestinal motility is largely unexplored. The region or regions of abnormal motility in 13 patients with a gastrointestinal motility disorder were characterized manometrically. Antral hypomotility was established in 6 patients and intestinal dysmotility in 7 others. One patient had both antral hypomotility and intestinal dysmotility. Gastric emptying of solids and liquids was quantitated scintigraphically; emptying data for solids were represented by a two-phase model (lag and emptying) and for liquids by a power exponential model. Antral hypomotility was associated with gastric stasis manifested by both a prolongation of the solid lag time [from 35 +/- 6 min for controls to 87 +/- 23 min (mean +/- SE), p less than 0.05] and slower emptying rates of solids (from a slope index of 29.9 +/- 2 for controls to 17.8 +/- 5, p less than 0.05) and liquids (from a kappa index of 3.6 +/- 0.6 for controls to 1.5 +/- 0.5, p less than 0.05). Intestinal dysmotility did not alter the solid lag time; however, it did decrease the slope of solid emptying from the stomach (from a slope index of 29.9 +/- 2 for controls to 13.5 +/- 3, p less than 0.05) and also prolonged emptying of liquids (from a kappa index of 3.6 +/- 0.3 for controls to 1.9 +/- 0.6, p less than 0.05). These data are consistent with the hypothesis that the gastric stasis in gut dysmotilities occurs because of impaired antral peristalsis due to antral hypomotility or increased resistance to flow into the small bowel due to intestinal dysmotility.