The effect of metoclopramide, a stimulant of gastric motility, on gastric emptying was tested in 6 patients with chronic gastric retention after vagotomy and gastric resection, unexplained by mechanical obstruction or stomal ulceration. Gastric emptying was measured using a gamma camera technique and a solid meal labeled with 99mtechnetium-labeled diethylenetriaminepentaacetic acid. Metoclopramide produced a 2.6-fold increase in gastric emptying in the first 90 min after eating the meal, compared to placebo (P less than 0.01). Metoclopramide did not alter gastric emptying in 8 normal volunteers. These data indicate that metoclopramide may be useful in treatment of patients with chronically impaired gastric emptying after gastric surgery.