Between 1978 and 1990, 32 patients (15 men and 17 women; mean age 48 (range 15-83) years) underwent 35 operations for renal artery aneurysm (4.2% of 829 renal artery repairs). Eleven patients presented with acute symptoms (nine with hematuria, eight with abdominal pain, two with acute hypertension). Twenty-eight of the 32 patients had chronic hypertension. The diagnosis was confirmed by angiography in all but two. The mean diameter of the renal artery aneurysm was 1.7 (range 0.7-9.0) cm. Seventeen patients had concomitant renal artery stenosis; none of the aneurysms ruptured. Nephrectomy was performed in seven patients and excision of the aneurysm without reconstruction in five. Twenty patients underwent 23 reconstructions using lateral suture (three procedures), vein patch (three), saphenous vein (13), Dacron (three) or composite (vein and hypogastric artery) graft (one). Seven patients underwent ex vivo renal artery repair. There was no perioperative death or secondary nephrectomy. One postoperative graft occlusion was successfully revised. Hypertension improved in 50% of patients. The presence of hypertension, enlargement of a renal artery aneurysm, solitary kidney, bilateral involvement, acute hematuria or potential loss of kidney or renal function may be indications for surgical treatment of an aneurysm > 1.5 cm in diameter. A renal artery aneurysm of any size should be repaired in women who may become pregnant. Where there is branch involvement, ex vivo repair is the procedure of choice for renal salvage.