The authors evaluated the in vivo effects of the new drug Cisapride on gastrointestinal hormone release in the mini-pig. Cisapride has been reported to stimulate and coordinate peristalsis of the GI tract. Selective endoluminal perfusion with Cisapride solution of the isolated but not denervated gastric antrum, duodenum and distal ileum demonstrated a significant increase of gastrin levels following perfusion of the gastric antrum and a decrease in vasoactive intestinal peptide following perfusion of the duodenum, only at very high doses.