['To evaluate the association between F11 rs2289252, rs2036914 polymorphisms and the activity of clotting factor XI in post-trauma patients with fractures receiving routine anticoagulation therapy for deep venous thrombosis (DVT).', 'A case-control study involving 110 consecutive post-trauma patients with fractures and DVT in our hospital was conducted from April 2014 to October 2015; these patients comprised a DVT group. Another 40 sex- and age-matched patients with fractures but without DVT served as controls. Additionally, 40 sex- and age-matched healthy people were chosen as a normal group. Venous blood samples (2 mL) were drawn from all participants and genomic DNA extracted from the leukocytes of the patients with fracture-related DVT, whose genotype and allele frequency distribution of F11 gene rs2089252 and rs2036914 single nucleotide polymorphism were then assessed by a sequencing method. The activity of factor XI was measured by a solidification method in all participants, including those in control and normal groups.', 'The activity of factor XI in patients with fracture-related DVT and F11 rs2089252 CT was 1.16 times that of those with CC genotypes (P < 0.0001), whereas in patients with fracture-related DVT and F11 rs2089252 TT genotypes it was 1.32 times that of those with CC genotypes (P < 0.0001), in patients with fracture-related DVT and F11 rs2089252 T allele it was 1.24 times that of those with C allele (P < 0.05), in patients with fracture-related DVT and F11 rs2036914 CC it was 1.35 times that of those with TT genotypes, in patients with fracture-related DVT and F11 rs2036914 CT genotypes it was 1.12 times that of those with TT genotypes (P < 0.05), and in patients with fracture-related DVT F11 and rs2036914 C allele it was 1.22 times that of those with T allele (P < 0.05). The activity of factor XI was significantly higher in the control than in the normal group (P < 0.05).'] Do f11 rs2289252T and rs2036914C Polymorphisms Increase the Activity of Factor XI in Post-trauma Patients with Fractures Despite Thromboprophylaxis?