In this article we report the successful treatment of a lower descendi
ng thoracic aorta hydatidosis that mimicked a posterior saccular aneur
ysm; surgical excision was performed and the aorta was repaired with a
prosthetic Dacron patch. At a 26-month follow-up, the patient is aliv
e and conducting a normal life. Discussion about the management of thi
s rare case also is given.