PPARgamma belongs to the group of nuclear receptors which is expressed in the trophoblast and together with other factors is responsible for the maintenance of pregnancy. Apart from that PPARgamma is also a main factor for macrophage polarization. The aim of this study was to investigate the combined expression pattern and frequency of PPARgamma under physiological circumstances and in spontaneous and recurrent miscarriages in the trophoblast and in maternal macrophages of the decidua. Human placental tissues of the first trimester (15 physiologic pregnancies, 15 spontaneous abortion & 16 recurrent miscarriage placentas) were analyzed for expression of the nuclear receptor PPARgamma. Expression changes were evaluated by immunohistochemistry and RT-PCR in trophoblast and in maternal macrophages of the decidua. Maternal macrophages were identified by double immunofluorescence using CD68 as marker for macrophages. The intermediate villous trophoblast revealed a significantly lower PPARgamma expression in spontaneous and recurrent abortion. Maternal macrophages express PPARgamma. Their number is significantly enhanced in the decidua of spontaneous miscarriages whereas in recurrent miscarriages maternal macrophages seem to express PPARgamma only in very few cases. PPARgamma is associated with an M2 polarization state that is common for decidual macrophages. The lack of PPARgamma in recurrent miscarriage decidual macrophages seems to be associated with a specific inflammatory response against the fetus.