29 patients aged 11-55 years underwent surgery an aneurysm of the descending part of the thoracic aorta that had developed after a blunt chest trauma. In all patients continuity of the vessel was restored by interposition of a prosthesis. Surgery was performed during the acute stage in 5 patients, two of whom died postoperatively due to infection of the prosthesis and shock lung respectively. One of the 24 patients who were operated on during the chronic stage died on the 16th postoperative day of apoplexy. One of the 26 patients who were discharged from hospital after the operation died of a spurious aneurysm that had developed at the site of the prosthesis. Follow-up examinations of 21 patients showed normal postoperative function. In 5 cases there was an angiographically demonstrable slight narrowing at the site of the anastomosis; the pressure gradient, measured intravascularly, did not exceed 30 mm Hg.