The major portal of entry for most pathogenic microorganisms is the mucosal surface. It seems reasonable therefore that the host in its turn should possess substantial immune defences at the mucosae to provide protection against these insults. Enteric infections usually result in at least some degree of specific protection against a subsequent infection with the same organism. However artificial induction of mucosal immunity has proved difficult. Clearly, as yet, we do not have a full understanding of the inductive events involved in the generation of mucosal immune responses or the immune mechanisms operating at mucosal surfaces. In this paper I will attempt to briefly review the main aspects of mucosal immunity concentrating on the gut as the model mucosal surface.