Renal artery aneurysm is a rare condition defined as a dilated arterial segment which exceeds twice the diameter of the normal renal artery. Renal artery aneurysms are usually asymptomatic, and diagnosis is most often incidental. Morphology is classified as saccular (the most common), fusiform, dissecting, or mixed. The main risk factors for rupture include pregnancy, polyarteritis nodosa, and large aneurysm size.

Renal artery aneurysms are associated with fibromuscular dysplasia, atherosclerosis, vasculitis, trauma, and syphilis. Congenital renal artery aneurysms also occur. Aneurysms that are greater than 2.5 cm, growing, or causing renal complications such as renovascular hypertension or hematuria are usually treated surgically.