Over the years, the role of the eosinophil in asthma and allergic processes has been disputed. Recent human experiments using a humanised monoclonal antibody to interleukin-5 (IL-5), and animal studies involving specific IL-5 gene deletion, indicates that eosinophils might control downstream repair and remodelling processes. Eosinophils are a rich source of fibrogenic factors, particularly transforming growth factor-β (TGF-β), the latent form of which is activated by epithelial-cell expression of the intergin α vβ 6. The emerging role for the eosinophil in airway remodelling might be important in future anti-asthma strategies. However, more effective eosinophil-depleting agents than anti-IL-5 are required before the definitive role of this cell type in asthma airway pathophysiology can be established.