Within the past couple of years, peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear transcription factor expressed in vascular cells, has received growing interest in vascular biology and atherosclerosis research. Initially, PPARgamma was identified as a regulator of gene expression in lipid metabolism and adipogenesis, but recent data in monocyte/macrophages, endothelial cells, and vascular smooth muscle cells suggest that PPARgamma might have anti-inflammatory effects in atherogenesis. However, with growing insight, there is much controversy about potential anti- or proatherosclerotic effects. This review will focus on these aspects and discuss what PPARgamma activation in vascular cells could mean for atherogenesis and the development of atherosclerosis.