Tissue Factor (TF) is a membrane protein located on the cell surfaces of extravascular cells. TF activity is fundamental for normal homeostasis- the physiological process which leads to blood coagulation. Indirect evidences suggest that the membrane lipid composition and in particular the presence of anionic phospholipid, such as phosphatidylserine (PS), and cholesterol has an important impact in stabilizing the protein complex and thus in regulating TF activity towards blood coagulation. No experimental data has so far been published on the structure of TF in lipid membranes. Here we propose to prepare supported membrane with TF to investigate by means of NR the effect of PS and cholesterol on the TF location with respect to the membrane.