The interaction of blood with artificial surfaces is of particular interest during hemodialysis treatments with extracorporeal blood circuits. Components of the extracorporeal blood circuit are known to have only a moderate, sometimes even an unfavorable hemocompatibility, and thus may provoke adverse biochemical or clinical sequelae. This article describes a newly established hemocompatibility assessment score. This score is based on on a standardized series of in vitro tests and is applied to commercially available hemodialysis membranes. It relates to a variety of membrane polymers, such as regenerated cellulose, diethylaminoethyl-modified cellulose, polyethersulfone/polyarylate blends and polysulfone. In order to compare different polymers used in the manufacturing of dialysis membranes, a set of the following hemocompatibility parameters was assessed and assembled to an overall score: generation of complement factor 5a, thrombin-antithrombin III-complex, release of platelet factor 4, generation and release of elastase from polymorphonuclear granulocytes, and platelet count. With respect to these parameters, the results reveal major differences between the selected dialysis membranes. This new score model proves to be an efficient tool to derive objective results, and it may, thus, be used in the future to facilitate the selection of membrane polymers with an appropriate hemocompatibility pattern for dialysis therapy.