Although safe and effective, nephrolithotomy sometimes is difficult. 224 patients have undergone percutaneous stone extraction surgery. Two groups were established according to previous open renal surgery. 79 patients had had previous surgery and 145 patients were initially treated by percutaneous nephrolithotomy. Bleeding and operative time, i.e. puncture of the kidney, dilation of the tract and lithotripsy were greater in the group with previous renal surgery. However, no statistical difference was verified. In conclusion, percutaneous lithotripsy is a safe and effective method with minimal morbidity even in patients with previous renal surgery.