The aim of the study was the isolation and characterization of mesenchymal stem cells from the placental chorion from a genotypical and phenotypical point of view. The placentas included in the study were derived from term pregnancies with a normal evolution. Along with the placentas, umbilical cord blood, maternal and newborn peripheral blood samples were taken. The isolation and culture of chorionic and, incidentally, trophoblastic cells was followed by the determination of markers of the former cells. They expressed proteins and genes characteristic of stem cells. Immunofluorescence and evaluation of gene expression evidenced the pluripotential properties of these cells and also their higher position on the differentiation pathway. HLA expression provides information that might help explain the immunological mechanisms of tolerance between the maternal organism and fetal structures.