Objective: Endothelial microparticles(EMPs)are directly indicative of endothelial cell activation or apoptosis,and may also reflect endothelial inflammation,increased coagulation,and vascular tone.The aim of this study is to investigate whether EMPs would be able to evaluation system involvement and be a new indicators of disease activity in Behcets disease(BD).Methods: Thirty-nine consecutive BD patients(who fulfilled the modified International Study Group on Behcets disease in 1990 or International Criteria for Behcets Disease in 2006)and 30 age and sex-matched healthy controls were enrolled.The plasma levels of EMPs were measured by flow cytometry utilizing specific labels for endothelial MPs(CD31+and CD42b-).Results: The levels of circulating EMPs(CD31+and CD42b-)were significantly elevated in the case group compared with the HCs(p=0.000).Moreover,BD patients plasma EMPs were positively correlated with Behcets disease current activity form(r=0.802,p=0.000).Vascular involvement in BD patients than in patients without vascular EMPs were significantly increased,p=0.004.Gastrointestinal involvement in BD patients than in patients without Gastrointestinal EMPs were significantly increased(p=0.011).Conclusions: The elevated EMPs may be a potential indicator to predict disease activity of Behcets disease.The plasma level of EMPs was increased,which indicated the increased risk of vascular and digestive tract involvement in BD.