Background: Aortic root aneurysm involves dilatation of sinuses of Valsalva, sinotubular junction and proximal ascending aorta. It is a rare complication after aortic valve replacement surgery. Giant aneurysm is defined as aneurysm of size> 10 cm. Surgical treatment involves Bentall’s procedure. Case Detail: A 40 year old gentleman with severe aortic regurgitation and moderate aortic stenosis underwent aortic valve replacement with a mechanical prosthetic valve of size 25 mm, 13 years ago. At the time of this surgery the ascending aorta was mildly dilated, measured 3.5 cm in size. Patient came with complaints of breathlessness on exertion from past two months, NYHA class III. Echocardiography and CECT revealed giant ascending aortic aneurysm about 12.8 cm in diameter with intimal flap suggestive of dissection. Prosthetic valve function and other cardiac structures were assessed as normal. Elective surgery was planned. CPB established via right axillary artery and right femoral vein. Ascending aortic aneurysm was excised along with prosthetic mechanical valve. Bentall’s procedure was done using 27 mm Dacron composite graft. Patient required permanent pacemaker for complete heart block in post operative period. Thereafter patient was discharged in stable condition. Conclusion: Aortic aneurysm should be tackled surgically in order to decrease the morbidity and mortality. Regular follow up of such patients should be done.