We retrospectively compared morbidity and success rates in children who underwent percutaneous nephrolithotomy with 3 different sizes of instruments. Percutaneous nephrolithotomy was performed using adult instruments via a 26Fr tract in 23 patients, using pediatric instruments via a 20Fr tract in 13 and using minimal access (14Fr) in 10. Percutaneous nephrolithotomy was performed using general anesthesia with parenteral antibiotic prophylaxis. Cystoscopy and retrograde pyelography were performed, and 5Fr to 6Fr soft ureteral catheters were placed during each procedure initially. Percutaneous access was established via fluoroscopic guidance with the patient in the prone position. Pneumatic, ultrasonic and holmium laser lithotriptors were used for in situ lithotripsy. A 14Fr nephrostomy catheter was placed at the end of the procedure in the 26Fr and 20Fr groups, and in the minimal access group the ureteral stent was left indwelling in cases of atraumatic procedure with no residual fragments. Mean patient age was 13.2, 5.9 and 6.3 years, respectively, in the 26Fr, 20Fr and minimal access groups (p=0.000). Sex distribution, previous surgery, stone size, surgery and fluoroscopy times, mean hemoglobin decrease and hospitalization time did not differ between the groups. However, blood transfusion rate was higher in groups 1 and 2. Stone-free rates were 69.5%, 80% and 90%, respectively, in groups 1 to 3. Overall, adjuvant shock wave lithotripsy treatment was needed in 3 children. Smaller instrument size to 20Fr did not significantly increase the operative time, and resulted in the same success rates as the adult sized devices. However, low blood transfusion rates were only reached in the minimal access percutaneous nephrolithotomy group.