Bicuspid aortic valve (BAV) is a common congenital heart disease, and it is well known to be a risk factor for ascending aortic dilatation and dissection. We here report a case of 34-year-old woman who underwent Ross procedure with ascending aortic replacement under the diagnosis of subaortic stenosis and ascending aortic aneurysm. She was pointed out to have heart murmur soon after the birth diagnosed as patent ductus arteriosus. The ductus was ligated when she was 3-years-old, however, heart murmur remained. Further examinations revealed that she also had aortic stenosis with BAV. During her 20-year-follow-up, subaortic stenosis and ascending aorta ectasia were also progressed. Pathological examinations of resected ascending aortic wall showed mucoid degeneration and laceration of collagen fibers, suggesting the fragility of dilated aortic wall with BAV.