A model of lung eosinophilia based on the repeated exposure of mice to aerosolized OVA has been used to identify C–C chemokine genes expressed at stages of massive eosinophil infiltration. We describe the identification and cloning of a cDNA that encodes a mouse C–C chemokine with 68% amino acid identity to guinea pig Eotaxin. The recombinant protein encoded by this gene displays potent and specific chemotactic activity for eosinophils, both in vivo and in vitro. Its mRNA levels parallel the kinetics of eosinophil accumulation in the lung during the experimentally induced eosinophilia and it is mainly produced by type I alveolar epithelial cells. The mRNA expression of mouse Eotaxin is not restricted to Th2 T cells in vitro and is independent of the development of a Th2-type response during N. brasiliensis infection, in vivo.