Renal hemorrhage is the most worrisome complication of percutaneous renal surgery. Between August 1983 and August 1992 we performed 2,200 percutaneous renal operations, with 17 patients (0.8%) requiring angiography and embolization for significant bleeding uncontrolled by the usual measures. The angiographic diagnoses were arteriovenous fistula in 7 patients, pseudoaneurysm in 4, fistula and pseudoaneurysm in 2, and lacerated renal vessels in 2. A total of 15 patients required no further treatment after embolization, while 2 underwent either partial nephrectomy or open exploration. No risk factors for hemorrhage could be identified. We recommend angiography and embolization under 3 conditions; 1) in the immediate postoperative period when clamping of the nephrostomy tube and a tamponade balloon catheter fail to control hemorrhage (24% of our series), 2) in the early postoperative period (2 to 7 days) when the patient requires 3 or 4 units of blood after replacement of the initial blood loss (41% of our series) and 3) for sudden hemorrhage more than 7 days postoperatively (35% of our series).