The composition and molecular organization of adsorbed protein films are strongly correlated with thrombogenesis on artificial surfaces. In particular, the antibody-detectable (that is, conformationally intact) bound fibrinogen, but not that the total amount of adsorbed fibrinogen, is correlated with platelet reactivity. In this work, the authors quantified the adsorbed plasma protein distribution inside the left ventricular assist device. They also evaluated the effect of wall shear stress on protein adsorption and conformational change of adsorbed fibrinogen. Conformational change of adsorbed fibrinogen was measured by exposing the fibrinogen preadsorbed polyurethane to three anti-fibrinogen monoclonal antibodies; the 134B-29 detectable alpha 566-580 domain of fibrinogen was increased with increasing concentration of adsorbed fibrinogen, whereas the other two fibrinogen domains were almost saturated when increasing the concentration of adsorbed fibrinogen. The adsorbed amounts of total fibrinogen and monoclonal antibody detectable fibrinogen was decreased with increasing shear rate. Results of in vivo plasma protein adsorption on polyurethane surfaces disclosed that the adsorbed amount of fibrinogen, as well as albumin and globulin, was also decreased with increasing shear rate. In conclusion, less protein was adsorbed in the higher shear region and the effect of shear level on fibrinogen adsorption and its conformational change was strongly dependent upon the surface characteristics of the biomaterials. The monoclonal antibody 134B-29 against the 566-580 domain of fibrinogen was the most reactive with the fibrinogen adsorbed on polyurethane surfaces in this experiment.