CC chemokines are small inducible proteins that are related to interleukin 8. Recent studies have shown that several CC chemokines, MCP-1, MCP-3, RANTES and MIP-1 alpha, act on basophils and/or eosinophils via GTP-binding protein-coupled receptors. Marco Baggiolini and Clemens Dahinden discuss the involvement of CC chemokines in the recruitment and activation of the main effector cells of allergic inflammation.