Peroxisome proliferator-activated receptor gamma (PPARgamma) has been characterized as a regulator of adipocyte differentiation and lipid metabolism. However, in the last few years growing evidence indicates that PPARgamma plays an important role in controlling immune and inflammatory responses. Upregulation of PPARgamma expression is observed in asthmatic airways, and an involvement of PPARgamma in airway inflammation and airway hyperresponsiveness in asthma has been reported. Recent studies have demonstrated that PPARgamma ligands may have a therapeutic effect in asthma. This article reviews the latest knowledge and studies on the roles and mechanisms of PPARgamma and PPARgamma ligands in asthma.