High von Willebrand factor antigen (vWF:Ag) levels can be found due to vascular endothelial injury in Behç et disease. The aim of this study is to evaluate whether there is any relationship between vWF:Ag levels and vascular or other organ involvements and acute-phase reactants in Behç et disease. Fifteen controls and 17 Behç et's patients were included; 10 had oral ulcers, 5 had genital ulcers, 3 had skin lesions, 6 had ocular involvement, 5 had arthritis, and 6 had vascular involvement. VWF:Ag levels were higher in Behç et's patients than controls. VWF:Ag levels in Behç et's patients with oral ulcers, genital ulcers, and ocular and vascular involvement were statistically higher than in the control group. Differences between vWF:Ag levels in Behç et's patients with and without organ involvement were not statistically significant. A linear correlation between serum ferritin levels and vWF:Ag levels was observed. These results demonstrate that elevated levels of plasma vWF:Ag are related to Behç et disease exacerbation rather than vascular involvement. Am.