More than 180 million people worldwide are chronically infected with the hepatitis C virus (HCV), which is responsible for over 1 million deaths from cirrhosis and primary liver cancer yearly. HCV infection is associated with inflammation of liver endothelium, which contributes to the pathogenesis of chronic hepatitis. The strong correlation between markers of endothelial dysfunction and soluble adhesion molecules in patients with chronic hepatitis C strengthen the view that an ongoing stress on endothelial cells is present in these patients. This may play a pathophysiological role in the progression of disease. The von Willebrand factor (vWf) is released by endothelial cells in physiological conditions. Endothelial damage results in increased vWf release, thus it is an indicator of endothelial dysfunction. Our aim was to study the value of vWf in patients with chronic hepatitis C virus infection, as a possible indicator of endothelial dysfunction. Also, to test vWf as a possible indicator of progression, severity and morbidity of chronic liver disease. Our thesis includes 40 patients divided into 2 groups. The first group involves 30 subjects proven positive for hepatitis C virus by PCR. The second group involves 10 control subjects who should be negative for hepatitis C virus by PCR. VWF level was measured in the sera of all patients, as a marker of endothelial dysfunction.The results showed increased vWf levels in patients with chronic HCV infection, which correlated with severity of the disease.We concluded that chronic HCV infection is associated with endothelial dysfunction, and that serum vWf antigen level can be used as a predictor of liver disease progression.