The earliest attempts to protect humans against infectious diseases and toxins were by administering foreign substances to mucosal membranes, predominantly by the oral route. In the late 1880s, significant attention was given to the concept of 'local' immunisation, and the discipline of mucosal immunology was born in the early 1900s. However, despite the early enthusiasm, progress has been slow, with few mucosal vaccines being efficacious. The complexities of mucosal immune regulation and the lack of appropriate antigen delivery systems which can access mucosal inductive sites, have remained substantial obstacles. Recent studies demonstrating compartmentalisation of the common mucosal immune system create further challenges for the development of organ-specific vaccines. In the 21st century, our knowledge of mucosal immunoregulatory mechanisms, coupled with new technology for antigen delivery and immunomodulation will provide the necessary know-how to see the development and widespread use of mucosal vaccines for both preventative and therapeutic use.