Introduction. False aneurysms of the ascending aorta represent a rare but potentially fatal complication of cardiac surgical procedures. Predisposing factors are aortic dissection, infection, connective tissue disorders, chronic hypertension, aortic calcifications and aortotomy dehiscence. At the beginning they are usually asymptomatic, but later various symptoms arise as a consequence of vital structures compression. Potential risk of rupture rises with time and pseudoaneurysm enlargement. From surgical point of view treatment of such cases represents a unique challenge because of the great danger of inadvertent opening of the aneurysm during resternotomy. Case Outline. A 58-year-old female patient underwent aortic valve replacement due to severe aortic stenosis in 2004. Operation and postoperative recovery were uneventful. Three years later she started complaining about chest pain. On chest X-ray there was upper mediastinal widening. CT scan showed a pseudoaneurysm of the ascending aorta located in front of the right atrium and right ventricle, which was subsequently verified by angiography. During redo operation the pseudoaneurysm was successfully resected and aorta closed with separate ethybond sutures with pledgets. Conclusion. Postoperative pseudoaneurysms of the ascending aorta mostly arise from the suture lines. The most useful diagnostic procedures are contrast CT scan, echocardiography, angiography and MRI. Surgical intervention is absolutely indicated. The institution of cardiopulmonary bypass by alternative ways before chest opening is strongly recommended.