Aim To explore the clinical implications between plasma monocyte chemoattractant protein-1(MCP-1)levels and flow-mediated dilation(FMD)of brachial arteries in individuals with essential hypertension.Methods 42 patients with essential hypertension and 40 healthy controls were enrolled in the study.FMD on brachial artery at rest and during reactive hyperemia was assessed by high-resolution,two-dimensional ultrasonography.Plasma MCP-1,nitric oxide(NO)and von Willebrand factor(vWF)levels were also determined.Results Compared with controls,brachial artery FMD and NO level of hypertensive patients were significantly decreased(6.6%±2.6% vs 10.7%±1.8%,16.90±5.49 μmol/L vs 24.55±7.32 μmol/L,p<0.01).Plasma vWF,MCP-1 of hypertensive patients were markedly increased(122.02±63.53 ng/L vs 90.27±38.38 ng/L,p<0.01;19.94±8.95 ng/L vs 15.93±6.78 ng/L,p<0.05).The levels of MCP-1 were negatively correlated with FMD(r=-0.278,p<0.05).Conclusions Endothelium-dependent vasodilation is impaired in patients with essential hypertension,which is associated with the increased MCP-1 level.