Studies of human asthma and of animal models of allergic inflammation/asthma highlight a crucial role for T(H)2 cells in the pathogenesis of allergic asthma. Repressor of GATA (ROG) is a POZ (BTB) domain-containing Kruppel-type zinc finger family (or POK family) repressor. A repressive function to GATA3, a master transcription factor for T(H)2 cell differentiation, is indicated.The aim of this study was to clarify the regulatory roles of ROG in the pathogenesis of T(H)2-driven allergic diseases, such as allergic asthma.We examined allergic airway inflammation and airway hyperresponsiveness (AHR) in 3 different mouse models, which use either ROG-deficient (ROG(-/-)) mice, ROG transgenic mice, or adoptive transfer of cells.In ROG(-/-) mice T(H)2 cell differentiation, T(H)2 responses, eosinophilic airway inflammation, and AHR were enhanced. In ROG transgenic mice the levels of eosinophilic airway inflammation and AHR were dramatically reduced. Furthermore, adoptive transfer of T(H)2 cells with increased or decreased levels of ROG expression into the asthmatic mice resulted in reduced or enhanced airway inflammation, respectively.These results indicate that ROG regulates allergic airway inflammation and AHR in a negative manner, and thus ROG might represent another potential therapeutic target for the treatment of asthmatic patients.