Rupture of the aorta that usually occurs with major blunt trauma of the chest is associated with a high mortality, and only 2% of the patients survive long enough to develop a false aneurysm. Although symptom-free latent period is not rare, there is evidence of progression. Since 1970 we operated on 28 patients (24 male and 4 female, mean age 41.2 years) for chronic traumatic aneurysm of the descending aorta. A previous blunt trauma of the chest had certainly occurred in 23 cases (3 months to 20 years before) and was likely in 4 patients; in one young woman the aneurysm developed after percutaneous angioplasty of a coarctation. In 26 patients surgical repair consisted in a Dacron tube interposition, and in 2 cases patch repair was adequate. In 11 cases the "clamp and repair" technique was applied, while in 17 patients extracorporeal circulation was established to perform the reconstruction, two of these cases were operated with hypothermic circulatory arrest. Although there was no correlation between the occurrence of complications and the applied procedure, we lately turned to establish cardiopulmonary bypass in all cases with regard to a better control of the hemodynamics during clamping, the possibility of direct retransfusion of blood, and the option to extend the procedure, if necessary. In view of the facts, that traumatic thoracic aneurysms develop late complications in about 75% of the cases, and the morbidity in elective surgery is of a low figure, we conclude, that surgery of such lesions is mandatory, once the diagnosis has been established, and that an expectant attitude in the treatment is justified only in exceptional cases.