An exciting and rapidly evolving area in vascular biology and atherosclerosis research over the past 3 years has been the establishment of peroxisome proliferator-activated receptor (PPAR) expression in the vascular and inflammatory cells, and the emerging picture of the roles these ligand-activated nuclear receptor/transcription factors might play in vascular biology and atherosclerosis. Such work is all the more compelling given the ongoing clinical use of PPAR activators in patients. Thiazolidinediones (PPAR-g agonists) are used as insulin sensitizers in diabetic patients known to be at extraordinarily high risk for cardiovascular disease, whereas fibrates (PPAR-a agonists) are used to treat dyslipidemia, particularly in the case of high triglycerides and low high-density lipoprotein cholesterol.