DESIGN AND INTERVENTION This retrospective study included patients <15 years old treated for urolithiasis between 1995 and 2004. Eligible patients had stones of 1–2 cm diameter, without distal obstruction. All patients were preoperatively evaluated using excretory urography and, when available, noncontrast spiral CT. In patients with calculous anuria or impaired renal function, abdominal ultrasound, plain abdominal X-ray, and antegrade pyelography were used. Cultured urine specimens were also assessed. PCNL was performed under general anesthetic using fluoroscopic guidance; ultrasound guidance was used in patients with calculous anuria. In younger patients, tract dilatation was restricted to 22 Fr (7.3 mm) and stones were fragmented using ultrasonic lithotripsy. In older patients, maximum tract dilatation was 30 Fr (10 mm), allowing adult stone extraction instruments to be used. SWL using the electromagnetic Lithotriptor S® (Dornier Medical Systems, Inc., Marietta, Georgia) was performed under general anesthetic in younger patients and with IV sedation in older patients. SWL power was increased What is the best treatment modality for children with renal stones of 1–2 cm diameter?