Prostaglandin analogues appear to heal peptic ulcers no better than would be predicted from their ability to inhibit acid secretion. This implies that their cytoprotective properties, which are so dramatic in acute animal experiments, play no part in ulcer healing. Ulcer healing involves mucosal repair, whereas cytoprotection concerns preservation of normal mucosa, the two processes being conceptually different. If any general benefits of prostaglandin cytoprotection are to be harnessed to clinical ends, drug delivery systems that ensure long-lasting contact with the gastroduodenal mucosa may be needed.