['Increased levels of circulating von Willebrand factor (vWF) have been found in patients with inflammatory bowel disease (IBD); this increase may reflect either endothelial damage or systemic inflammation. Our aim was to evaluate serum vWF levels in patients with IBD and their correlation with clinical and biochemical disease activity.', 'We evaluated serum vWF levels in 32 patients with ulcerative colitis (UC) (10 active with increased acute-phase reactants (APR), 6 active with normal APR, 16 in remission), 27 with Crohn disease (CD) (10 active, 12 quiescent, and 5 quiescent with increased APR), and 31 healthy controls.', 'Mean levels of vWF were 100.1 (standard deviation (s), 51.4) in IBD and 89.9 (s, 36.9) in controls (P = 0.33). Only five (8.47%) patients (three with active UC, one with active CD, and one with inactive CD but increased APR) showed circulating vWF levels higher than the upper limit of normal (150), compared with 1 (3.2%) of controls (P = 0.32). Among CD patients vWF levels were 80.0+/-25.4 in patients with quiescent disease and normal APR, 123.3+/-63.4 in patients with active disease (P = 0.04 versus inactive with normal APR), and 135.8+/-90.0 in patients with quiescent disease and increased APR (P = 0.059 versus inactive with normal APR). Among UC patients vWF levels were 82.7+/-35.6 in patients with quiescent disease and normal APR and 125.1+/-54.2 in those with active disease and increased APR (P = 0.002). Overall, mean vWF levels were significantly higher in patients with increased APR than in patients with normal APR (P = 0.0005) and controls (P = 0.009).'] Are serum von Willebrand factor levels in patients with inflammatory bowel disease related to systemic inflammation?