Objective: The present study was performed to study the role of Doppler ultrasonography in the assessment of endothelial function in patients with Behcet’s disease. Correlation with disease activity, clinical manifestations and laboratory investigations was performed.Patients & Methods: Thirty Behcet’s disease (BD) patients diagnosed according to the criteria published by the International Study Group for Behcet’s Disease in 1990 were included in this work. The patients were subjected to the following: Full history taking and clinical examination including ophthalmic, skin examination and Doppler ultrasonography (US) of the brachial artery. Routine laboratory tests including complete blood count (CBC), erythrocyte sedimentation rate (ESR), c-reactive protein (CRP), liver and kidney function tests and lipid profile were also done. Body mass index was calculated and skin pathergy test was performed.Ten healthy adults of matched age and sex served as control.Results: The patients age ranged from 26 to 45 years with a mean of 33.1±4.9 years and their disease duration ranged from 1 to 18 years with a mean of 5.8±4.1 years and the mean age at disease onset was 27.3±5.2 years. The mean base line diameter of the brachial artery was 3.6 ± 0.8 mm and no significant difference was found between it and that of the control group (p = 0.723) , the mean flow mediated dilatation (FMD) in BD patients was 8.1± 6.4% and it was significantly reduced in comparison to that of the control group (p = 0.044). The mean of the base line diameter in BD patients with vascular involvement was found not significantly different from those without vascular involvement or to healthy controls (p = 0.858). The FMD was significantly lower in BD patients with vascular involvement than those without any vascular involvement or to healthy controls (p = 0.007). The correlation between albumin and FMD whether non-vascular or vascular was positive and significant (r= 0.74 and 0.89 respectively).Conclusion: We conclude that there is evidence of subclinical atherosclerosis in patients with disease and endothelial dysfunction plays an important role in both early and later stage of coronary artery disease. Endothelial dysfunction documented by brachial artery FMD is a feature of BD, and it is more prominent in patients with vascular involvement. Measurement of brachial artery flow-mediated dilation may provide a simple, reproducible and noninvasive technique to identify patients at increased risk of vascular disease.