We present a neonate with a large saccular aneurysm of the thoracoabdominal aorta, extending from the intrathoracic aorta to the left common iliac artery. No underlying cause could be identified. Despite an early diagnosis, the aneurysm was deemed inoperable because of the lengthy involvement and the frail aspect of all visceral arteries. A review of the literature on congenital abdominal aortic aneurysm in infants was conducted. Eleven cases of live-born infants with a congenital abdominal aortic aneurysm have previously been published. None of them involved as large a part of the thoracic and abdominal aorta as the case presented here.