In March 2001, the European Commission funded a 3-year project (contract no. QLK3-CT-2000-00340) under the fifth Framework Programme to develop and test prototype products based on the oral delivery of vaccine and therapeutic agents using harmless lactic acid bacteria (LAB). The project, best known under its acronym LABDEL (for LAB delivery) also included research on LAB fermentation and technological innovations aimed at enhancing the efficiency of LAB delivery systems (1). One of the key scientific objectives was to investigate the possibility to prevent or treat a type I allergic disease using mucosal administration of LAB expressing the pollen allergen Bet v 1. The aim of this paper was to describe the background of the project with reference to a limited selection of articles and recent reviews as well as the results and major conclusions arising from this part of the project.