To evaluate the role of adhesion molecules and chemokines in the relationship between air pollution and asthma, the authors determined the following in 230 children who lived in 4 communities in Japan that had different levels of air pollution: serum concentrations of soluble intercellular adhesion molecule-1 (sICAM-1); soluble vascular cell adhesion molecule-1 (sVCAM-1); regulated on activation, normal T-cell expressed and secreted (RANTES); and total immunoglobulin E (IgE). Children with asthma or who exhibited wheezing (n = 115) and nonasthmatic children (n = 115) were studied. Serum concentrations of sICAM-1, sVCAM-1, and RANTES were increased significantly in asthmatic children, compared with nonasthmatic children. Nonasthmatic children with serum IgE levels that were greater than or equal to 250 IU/ml had significantly lower concentrations of sICAM-1 and sVCAM-1 than the other children. The geometric means of sICAM-1 increased as air pollution increased. The results of this study suggest that adhesion molecules or chemokines are associated with asthma and that ICAM-1 may play an important role in the relationship between air pollution and the occurrence of asthma.