Peroxisome Proliferator-Activated Receptor g (PPARg) belongs to the nuclear receptor dependent ligand-activated transcription factors that regulates expression of many genes involved in metabolism, cell differentiation, adipogenesis, inflammation and apoptosis. Despite numerous studies which have been published on PPARg activation during ectodermal differentiation, there are a limited number of studies on the role of PPARg in endodermal differentiation. Thus, the aim of this study was to assess the expression of PPARg during in vitro differentiation of mouse embryonic stem cells (mESCs) into definitive endoderm (DE). In this study we demonstrated that an increase of PPARg expression profile occurred upon retinoic acid (RA) treatment in the process of differentiation. This may arise from a possible role of PPARg in the process of endodermal differentiation which should be clarified in further studies.