The effect of metoclopramide has been studied on the emptying of solid meals labelled with (51)Cr and monitored with a gamma camera. Metoclopramide, 10 mg iv or a dummy injection, was given randomly and double blind to 10 normal subjects and to 10 patients within three months of a truncal vagotomy and pyloroplasty. All were tested in the recumbent position. Metoclopramide had no effect on emptying rates in the normal subjects nor in four postvagotomy patients who had emptying within the normal range (T(1/2) 30-150 min). In six patients with abnormally delayed emptying (mean T(1/2) 369 min) metoclopramide produced a significant improvement (mean T(1/2) 194 min, p < 0.01).