The role of afferent sensory neurones in gastric mucosal protection is discussed. The principal effects of substance P and capsaicin on gastric motility and mucosal blood flow are taken in correlation with gastric mucosal injury. It seems likely that the protective effect of sensory neuropeptides is dependent on gastric mucosal blood flow and is mediated through the nitric oxide-generating system and partly the prostaglandins. The interaction between these two systems and the primordial effect of one of them on gastric mucosal blood flow and mucosal integrity after neuropeptide release is still not clear.