FXI inhibition reduces thrombin generation and platelet activation. Local and systemic TAT (A,B) and βTG (C,D) levels were monitored during thrombus formation. Blood samples were also tested for the fibrinolysis product D-dimer (E). Local values are those taken from the near wall, low flow concentration boundary layer, 1 cm distal to the growing thrombus, over the course of 10 minutes before its designated time; systemic samples were taken from the arteriovenous shunt proximal to the thrombogenic device. Zero time points in all groups are from samples taken systemically immediately before each study. FXI inhibition (n = 6) was associated with a reduction in local thrombin formation and platelet activation, which translated into lower systemic TAT and βTG levels in aXIMab-treated animals than in collagen controls (n = 7), within 60 minutes after treatment. No significant change in D-dimer release during acute thrombus formation (≤ 60 minutes) was detected in aXIMab-treated and control animals. The silicone rubber tubing without the collagen-coated graft segment (n = 5) did not induce significant increases in coagulation or platelet activation during these studies. Values are means plus or minus SEM.