Recent clinical history suggests that bileaflet prosthetic valve leakage flow may initiate thrombosis. These studies investigated the effects of bileaflet prosthesis leakage flow on various markers of blood damage in an in-vitro environment. Results indicate that platelets are mechanically disrupted by the leakage flow stimulus, and that erythrocytes are more resistant to this mechanical disruption than platelets. In addition, results identify two markers of platelet damage which are sensitive to a leakage flow stimulus.