Percutaneous angioplasty was attempted in 5 patients with acute renal failure due to occlusion of the artery to a solitary functioning kidney. Angioplasty was technically successful in all patients. Renal function was completely restored in 3 and renal perfusion improved in 1 patient. In the fifth patient, renal function did not return despite ultrasound and radionuclide scan evidence of renal reperfusion. Transcatheter thrombolytic therapy was attempted in 2 patients, 1 of whom also underwent angioplasty. In this patient, perfusion was restored to most of the kidney. In the other patient an infrarenal aortic occlusion was present. During thrombolytic therapy, intrarenal microembolization occurred from lysis of the aortic thrombus, leading to irreversible renal damage.