Background: Acute renal failure due to renal ischemia/reperfusion (IR) injury is a significant clinical problem in cardiovascular surgery. Reactive oxygen species and inflammation play essential roles in the pathophysiology of IR injury. Matrix metalloproteinases (MMPs) are enzymes that play important roles in inflammation and mediate extracellular matrix degradation. It is known that peroxisome proliferatoreactivated receptor-gamma agonists have antiinflammatory and antioxidant effects. In the present study, we aimed to investigate the effects of pioglitazone, a synthetic peroxisome proliferatoreactivated receptor-gamma agonist, on MMPs and oxidative stress in a renal IR injury model in rats.