A 16-year-old female patient in whom a biologic aortic valve was implanted for bicuspid aortic valve, aortic stenosis with aortic regurgitation one year ago and discharged uneventfully was re-admitted to our clinic with dyspnea on exertion and fatigue. Transthoracic echocardiography revealed valvular aortic stenosis (a peak pressure gradient of 48 mmHg), second degree aortic regurgitation and sinus valsalva aneurysm. Multislice computed tomography angiography produced an image which was associated with sinus valsalva aneurysm at the subvalvular level or a pseudoaneurysm. She underwent mechanical aortic valve replacement and reconstruction of both valvular and subvalvular areas with a Dacron patch. After an uneventful recovery stay in the intensive care unit, the patient was discharged in the sixth postoperative day. This case highlights the development of a mitral-aortic intervalvular fibrosa pseudoaneurysm as a rare complication of aortic valve replacement.