Peroxisome proliferator-activated receptors (PPARs) are key nuclear receptors which mediate the regulation of the transcription of many genes, especially those involved in lipid catabolism and inflammation. In mammals, three types of PPARs named PPARa, PPARb (also called PPARd), and PPARg have been identified. Up and down-regulations of one or more of these receptors are encountered during development , physiological adaptations, and in several diseases. Therefore, the ability to accurately measure PPAR expression in cells and tissues is an important aspect of PPAR research. This can be done by Western blot with specific antibodies. In this chapter, we describe the use of our techniques (Cardiovasc Res 84: 83-90, 2009; PLoS One 5: e11494, 2010) to measure PPARs expression, describe the adequate way to extract proteins, the best antibodies currently available and discuss potential misleading results in the absence of appropriate controls.