Background: Coronary artery ectasia (CAE) is a well-recognized but relatively uncommon finding encountered during diagnostic coronary angiography. It is commonly defined as in appropriate dilation of the coronary arteries exceeding the largest diameter of an adjacent normal vessel more than 1.5-fold. CAE is not an isolated and benign disease but a reflection of a generalized vascular media defect. Objective: The aim of this study was to compare 2D-TTEand 3D-TTE measurements of the aortic root diameter in patients with coronary artery ectasia to assess the presence of aortic root dilatation. Patients and methods: This prospective observational study included 50 consecutive patients came to the Department of Cardiology, Al-Azhar University Hospital, New Damietta for coronary angiography. The study was carried out from November 2017 until December 2018. Injection aortography was used as a gold standard and to assess the presence of ascending aorta dilatation in those patients. Results: The present study shows that there was a good correlation between 3D-TTE and aortography at the levels of aortic annulus, sinuses of Valsalva, sinotubular junction (r =0.98,0.95,0.98) but a rough correlation between 2D-TTE and aortography at these levels (r =0.49,0.48,0.46). The present study shows that there was increase prevalence of aortic root dilatation 13 patients (26%) and ascending aorta dilatation 9patients(18%) in patients with CAE. Conclusions: Accuracy of aortic root measurement by 3DTTE was superior to that by 2DTTE, because the values by 2DTTE were underestimated compared to those measured by 3DTTE and aortography. Increase prevalence of aortic root dilatation and ascending aorta dilatation in patients with coronary artery ectasia. Dilated Ascending aorta was associated with a higher prevalence of aortic root dilatation.