Prostaglandin analogues have been expected to outperform other antisecretory drugs as ulcer healing agents. This expectation arises from their ability to combine 'cytoprotection' with gastric secretory inhibition. Evidence of the existence of these two separate functions abounds in animals and in humans, but a clinical advantage has not evolved. Whereas most clinical trials show no difference between prostaglandin analogues and H2-receptor antagonists, some studies have shown the prostaglandins to be significantly less effective or no better than placebo. The role of cytoprotection in ulcer healing (as opposed to prevention) may be questioned and the present clinical role for these agents is unclear.