Trimoprostil is a synthetic prostaglandin E2 derivative and prostanoid receptor agonist, with potential gastric secretion inhibitor and antiulcerogenic activity. It has been shown to reduce hydrogen ion secretion, to enhance gastric bicarbonate secretion and to reduce aspirin-induced gastric mucosal injury. In contrast to many E prostaglandins, it does not lower the tone of the lower oesophageal sphincter. Trimoprostil was well tolerated and more effective than placebo in the treatment of mild to moderate symptomatic reflux oesophagitis. It may be protective to human squamous oesophageal mucosa. Trimoprostil was not as effective as cimetidine in the treatment of duodenal ulcer.