The passage of a single oral dose of barium sulfate through the stomach and small intestine of 18 pigs (1 to 21 days of age) was studied. In a series of lateral radiographs, the stomach had a smooth oval appearance, filling the cranial third of the abdomen. Barium mixed rapidly with the milk clot in the stomach immediately after swallowing and became distributed throughout the stomach (except for the diverticulum, which contained gas). Barium passed into the duodenum by postdosing minute (PDM) 3 in 1 pig, and by PDM 10 in 11 pigs. In 32 experiments in 17 pigs, gastric emptying of barium was complete by PDM 100 in 91% of the experiments, whether or not the pigs had suckled the sow. Suckling also did not influence the time taken for barium to reach the large intestine (by PDM 360 in 12 pigs). When a hyperosmolar contrast medium (diatrizoate meglumine) was given instead of barium sulfate to 10 pigs, gastric emptying was delayed (it was not complete by up to PDM 218), but the small intestine filled rapidly (the contrast medium reached the cecum by PDM 218).