Objectives Behcet Disease (BD) is a multi-system inflammatory disorder as its underlying pathological process. Cardiovascular involvements have been reported in 7–46% of cases with Behcet's disease. We reported a case of Behcet's disease with severe aortic root vasculitis. Traditional two-dimensional echocardiography (2DE) demonstrated a dissection between anterior wall of the aortic root and interventricular septum associated with a rupture of left Valsalva sinus aneurysm into the left ventricular outflow tract. However, preoperative transesophageal real- time three-dimensional echocardiography (3DE) revealed that the aneurysm-like structure in left ventricular outflow tract involved the most part of the left ventricular outflow tract wall. The diagnosis was corrected by 3DE as the dissection between the ventricular septum and aortic root associated with a perforation of left Valsalva sinus and a prolapse of the exfoliated endocardium into the left ventricular outflow tract. These findings were confirmed during open heart surgery. Conclusion: 3DE is helpful to differentiate the dissection in the aortic root from the rupture of Valsalva aneurysm, especially in demonstrating the extent of aneurysm-like structure in the left ventricular outflow tract.