AIM: To investigate the clinical significance of serum vascular endothelial growth factor (VEGF) and soluble VEGF receptor-1 (VEGFRl/Flt-1) (sVEGFR1) levels in biliary diseases. METHODS: We analyzed the serum levels of these proteins in patients with acute cholangitis (group 1), biliary malignancies (group 2), and primary biliary cirrhosis or primary sclerosing cholangitis (group 3), and in healthy donors (group 4). The influence of inflammation was also analyzed. Serum VEGF levels were expressed as VEGF per platelet (VEGF/PLT, pg/106) in order to exclude the influence of platelet counts. RESULTS: sVEGFRl levels were significantly higher in groups 1 and 2 than in the control group, but did not correlate with inflammatory markers. VEGF/PLT levels were generally higher in patients with active inflammation than in those with carcinoma. C-reactive protein strongly correlated with the levels of serum VEGF independently of platelet and leukocyte counts, even in cancer patients. In cancer patients, VEGF/PLT and sVEGFRl levels might be indicators for evaluating the effect of medical treatment or the disease progression. CONCLUSION: Serum VEGF and VEGFR1 might be useful markers for gauging the clinical effect of various treatments on patients. AIM: To investigate the clinical significance of serum vascular endothelial growth factor (VEGF) and soluble VEGF receptor-1 (VEGFRl / Flt-1) (sVEGFR1) levels in biliary diseases. METHODS: We analyzed the serum levels of these proteins in patients with acute cholangitis (group 1), biliary malignancies (group 2), and primary biliary cirrhosis or primary sclerosing cholangitis (group 3), and in healthy donors (group 4). The influence of inflammation was also analyzed. Serum VEGF levels were expressed as VEGF / PLT, pg / 106) in order to exclude the influence of platelet counts. RESULTS: sVEGFR1 levels were significantly higher in groups 1 and 2 than in the control group, but did not correlate with inflammatory markers. VEGF / PLT levels were generally higher in patients with active inflammation than in those with carcinoma. C-reactive protein strongly correlated with the levels of serum VEGF independently of platelet and leukocyte counts, even in cancer patients. In cancer pat ients, VEGF / PLT and sVEGFR1 levels might be indicators for evaluating the effect of medical treatment or the disease progression. CONCLUSION: Serum VEGF and VEGFR1 might be useful markers for gauging the clinical effect of various treatments on patients.