Pseudo-aneurysms of the ascending aorta are a rare but serious complication of surgery for acute dissection of the aorta. The diagnostic methods and surgical technique have changed in recent years. The authors report their experience over a period of 20 years. From January 1981 to December 2001, 21 patients underwent reoperation for pseudo-aneurysms of the ascending aorta. The average age was 54.2 +/- 3 years. Diagnosis is no longer based on aortography but on transthoracic or oesophageal multiplane echocardiography, thoracic spiral computed tomography or magnetic resonance imaging. Four patients presented with a recent history of severe pulmonary oedema. The risk associated with reopening the sternum is avoided by current operative techniques. The authors have chosen anterograde perfusion of the cervical arteries by direct canulation for cerebral protection. The operative mortality at one month is high (30%). All patients who had pulmonary oedema or cardiogenic shock in the immediate preoperative period died. There were no neurological complications. Twelve patients survived and one has to undergo a further operation for recurrence of the pseudo-aneurysm. The authors conclude that patients operated for dissection of the aorta must be followed up. It is important to resect as much as possible of the pathological aorta during the initial operation to avoid the risk of pseudo-aneurysm formation, at least in the proximal segment of the ascending aorta.