1. In sheep, provided with re-entrant cannulas in the caudal duodenum and with an infusion tube into the abomasal fundus, emptying of the liquid phase of the abomasal contents was studied with [57Co]EDTA. Radioactivity was measured continuously with Geiger-Müller counters placed along the re-entrant cannulas. 2. It appeared that first-order kinetics could be applied to the elimination of [57Co]EDTA from the abomasum. Mean retention time of this label in the abomasum was 40–50 min. 3. Infusion of a suspension of soya-bean protein in saline (9 g sodium chloride/l) caused an initially decreased rate of abomasal emptying, but after 48 h an adaptation had occurred to the original rate of emptying producing an increased volume of abomasal contents and increased flow-rate of digesta into the duodenum.