Mitral-aortic intervalvular fibrosa is a thin and translucent junctional zone between mitral and aortic valve annulus. Aortic regurgitation jet flow or infection of this tissue may result in fistula or pseudoaneurysms. 44-year-old male patient was admitted to the hospital 5 months ago with shortness of breath, fever and excessive sweating complaints. in our case most applied surgical procedure is an aortic valve replacement and the aneurysm was closed through the aortic side of the aortic annulus with a bovine pericardial patch. The patient recovered well and was discharged on the tenth postoperative day.