The intervillous space (IVS) is part of the histofunctional unit of the human placenta and by being a fetal-maternal exchange interface is an important subject of study for the understanding of fetal physiology, especially in nutritional investigations. A method developed for the collection of IVS blood has permitted to evaluate the fetalmaternal exchanges in an effective manner. Two disadvantages of this method, however, are the mixing of IVS blood and fetal blood and marked hemolysis. In the present study we introduce and describe some modifications of this method using a single stylet for the perforation of the chorionic plate which simplifies collection and reduces the chance of mixing and hemolysis of the samples obtained.