Studies of human asthma and of animal models of allergic airway inflammation revealed a crucial role for Th2 cells in the pathogenesis of allergic asthma. Kruppel-type zinc finger proteins are the largest family of a regulatory transcription factor for cellular development and function. Zinc finger protein (Zfp) 35 is an 18-zinc finger motif-containing Kruppel-type zinc finger protein, while its function remains largely unknown. The aim of this study was to clarify the role of Zfp35 in the pathogenesis of Th2-dependent allergic inflammation, such as allergic asthma. We examined airway eosinophilic inflammation and hyperresponsiveness in two mouse models, which use our newly generated Zfp35-deficient (Zfp35(-/-)) mice and adoptive transfer of cells. In Zfp35(-/-) mice, Th2 cell differentiation, Th2 cytokine production, eosinophilic inflammation, and airway hyperresponsiveness were substantially enhanced. Furthermore, adoptive transfer of Ag-sensitized Zfp35(-/-) CD4 T cells into the asthmatic mice resulted in enhanced airway inflammation and airway hyperresponsiveness. These results indicate that Zfp35 controls Th2 cell differentiation, allergic airway inflammation, and airway hyperresponsiveness in a negative manner. Thus, Zfp35 may control Th2-dependent diseases, such as allergic asthma.