Glucocorticoids (GC) exert a variety of important anti-inflammatory actions. We have studied their effects in allergic inflammation and believe that their anti-allergic effects reflect their anti-inflammatory activities in general. These effects include inhibition of cytokine and other mediator secretion, inhibition of leucocyte priming in eosinophils and neutrophils, reduction of vascular permeability, inhibition of arachidonic acid metabolite and platelet activating factor (PAF) release, synergistic or permissive effects on responses to other mediators, such as catecholamines and other endogenous hormone-like molecules, and modulation of enzyme systems involved in inflammation. Glucocorticoid actions are thus multifaceted; this feature explains both their unequalled efficacy in inflammatory diseases and the difficulty in replacing them with other medications that have a uni-dimensional profile of action.