I. Introduction Asttuna is now widely recognized as a chronic inflammatory disease of the lungs, with the accumulation of activated eosinophils and T cells in the airways correlated with severity of the disease (1-4). The molecular mechanisms regulating the influx, activation, and prolonged survival of these cells in the asthmatic lung are poorly understood, although an interrelationship of cytokines, adhesion molecules, and chemokines has been suggested to mediate the selective recruitment of these and other cells. Several excellent reviews on general aspects of leukocyte-endothelial adhesion (5-7) and its role in asthma (8-11) are available, and we would recommend these to the reader seeking in-depth discussion of this area. This chapter aims to provide a concise description of the function of leukocyte-endothelial cell adhesion molecules and discuss that evidence demonstrating a role for these molecules in the pathophysiological characteristics of allergic airway inflammation in humans.