In this work we describe experiments designed to understand the blood compatibility and resistance to platelet adhesion of poly[bis(trifluoroethoxy)phosphazene] (Acta Polymerica 36, 627 (1985)) (PTFEP) coated surfaces. We compare quantitative in vitro protein adsorption measurements using enzyme linked inmunosorbent assays (ELISA) and platelet adherence tests on PTFEP with other organic surfaces and hydroxylated glass. Compared to some materials of medical interest (polymethylmethacrylate and silicone) and other materials (hydroxylated glass, aldehyde-, alkyl-, or amino-terminated surfaces) exhibiting a wide range of physical properties, PTFEP showed the highest human serum albumin adsorption and the lowest adsorption of fibrinogen and fibronectin. These proteins are related to thrombus formation and cellular attachment, respectively. Coagulation-stimulating proteins are predominantly bound reversibly on PTFEP and do not appear to denaturate to the extent found on the other surfaces.