Release of mucus as a consequence of superficial injury to the gastric mucosa appears to play an important role in providing a microenvironment suitable for rapid re-epithelialization, or restitution, to occur. Evidence is presented in this paper to support this hypothesis. Firstly, disruption of the cap of mucus which forms over a site of damage, either mechanically or through the topical application of mucolytic agents, results in retardation of the restitution process. Secondly, the mucoid cap is shown to act as a trap to plasma released as a consequence of the damage. Thirdly, the mucoid cap provides a region of high pH (4 to 6), despite the presence in the lumen of a solution with a pH of 1.3. Based on the data presented in this report, and previous work from this laboratory and others, a functional model for extracellular mucus in promoting mucosal restitution is proposed.