The application of streaming potential measurements in support of the development of blood compatible polymers is reviewed. Current knowledge about the relevance of interfacial charge of materials with respect to thrombogenicity of and coagulation activation by medical devices is discussed. Advanced applications of streaming potential measurements for the characterization of biomedical polymers comprise the in situ characterization of protein adsorption processes onto polymer solids. This approach is demonstrated for the adsorption of the blood plasma proteins albumin and fibrinogen onto a fluorocarbon polymer substrate.