Hydroxyl-terminated polybutadiene (HTPB)- and 4,4＇-dicyclohexyl-methane (H12MDI)-based polyurethanes (PUs) were synthesized by solution polymerization. PU membranes were prepared by a dry/wet phase inversion method. Protein adsorption ratio of fibrinogen to albumin (F/A molar ratio) was measured. Low F/A molar ratio was found on these PUs. It was found that surface composition of these PUs has a subtle effect on F/A adsorption molar ratio. The F/A molar ratio was increased as the increase of hard segment content distributed on the surface. The variation of surface composition of these membranes and the effect on the F/A molar ratio were investigated by the difference in surface energy between nonpolar HTPB soft segment and polar hard segment, concentration, and temperature of coagulation medium, polymer content, and alcohol type. The C=O/C=C ratio, frequency shift, and difference (Delta nu) as a measure of polymer homogeneity and the average strength of interpolymer hydrogen bonds were utilized to study the surface composition.