OBJECTIVE: We present our experience with percutaneous nephrolithotomy (PCNL) for management of large renal calculi in children less than 5 years old, and determine its safety and efficacy when using an adult-size device. PATIENTS AND METHODS: Twenty patients younger than 5 years old underwent PCNL between August 2003 and July 2008. After retrograde catheterization, the nephrostomy tract dilated up to 26Fr. Then a 24-Fr rigid nephroscope was used and stones were fragmented with a pneumatic lithotripter. RESULTS: Twenty patients with a mean age of 3.1 years underwent 26 PCNL procedures on 24 renal units. Four patients had bilateral renal stones. Five patients (20%) had staghorn stones, as did five of the other cases with multiple stones . Four patients had undergone previous stone surgery on the same side. All of the patients were managed with only one tract. The mean stone size was 33 (20-46)mm and average operative time was 93.25 (78-174)min. Stones were completely cleared in 79.16% of patients, which increased to 91.67% with adjunctive shockwave lithotripsy. The overall complication rate was 15.38% and mean hospital stay was 5.26 (3-8) days. CONCLUSION: PCNL is an effective and safe treatment for renal calculi in children less than 5 years old, even when using instruments designed for adults.