Current research in the field of atopy is directed almost exclusively towards treatment of established allergic disease. In particular, treatment has concentrated on controlling the release and actions of various mediators, such as cytokines, from the allergy effector cells at the end of the immuno-inflammatory cascade. Here, Patrick Holt argues that a potentially more-effective and achievable goal may be the prevention of initial T helper 2 (Th2)-cell sensitization to environmental allergens during infancy. This might be achieved via amplification of the endogenous 'immune deviation' mechanism(s) that normally facilitate discrimination between pathogenic and non-pathogenic antigens at the mucosal surfaces of the body.