Our interest is centered in understanding the role of PPARs (Peroxisome proliferator activated receptors) in the regulation of cell differentiation and lipid homeostasis in neurons. PPARs are the target of peroxisome proliferators, including hypolipidemic compounds used in the treatment of hyperlipemia, and of the thiazolendione antidiabetic drugs. They are activated by natural fatty acids and their metabolites (eicosanoids) and belong to the subfamily of nuclear receptors that includes the retinoic acid receptors (RARs) and thyroid hormone receptor (TRs). The PPAR subfamily is composed of three distinct subtypes, PPARalpha, PPARbeta and PPARgamma that form heterodimers with the retinoid X receptor (RXR). PPARalpha modulates the pleiotropic effects of peroxisomal proliferators, regulating genes involved in lipid catabolism, whereas PPARgamma affects key pathways in a variety of diseases, including insulin resistance and Syndrome X. PPARbeta is important in controlling other PPARs and in wound healing. PPARs have been best studied in systemic lipid metabolism, being involved in obesity, diabetes and cancer. Much less is known about their role in the nervous system. We have evidence to consider these receptors as potential pharmacological targets in the treatment of neurodegenerative diseases.