Degenerative arterial aneurysms can occur in any vascular territory. However, they are exceedingly rare in the axillary artery. Complications of axillary artery aneurysms may result in acute vascular insufficiency and neurological deficits. Prompt treatment should be employed in the management of this condition. We report a case of an atraumatic degenerative axillary artery aneurysm that was treated with transaxillary open surgical bypass.