Eosinophilic leukocytes accumulate in high numbers in the lungs of asthmatic patients, and are believed to be important in the pathogenesis of asthma. A potent eosinophil chemoattractant is produced in the asthmatic lung. This small protein, the chemokine eotaxin, is synthesized by a number of different cell types, and is stimulated by interleukin-4 and interleukin-13, which are produced by T-helper (Th)2 lymphocytes. Low molecular weight compounds have been developed that can block the eotaxin receptor C-C chemokine receptor (CCR)3, and prevent stimulation by eotaxin. This provides the potential for orally available drugs that can prevent eosinophil recruitment into the lung and the associated damage and dysfunction.