Purpose: We assessed the effect of tamsulosin as an adjunctive therapy after shock wave lithotripsy for pediatric single renal pelvic stones. Materials and Methods: A total of 120 children with a unilateral single renal pelvic stone were included in a prospective randomized, controlled study. All children were randomized to 2 equal groups. Group 1 received tamsulosin (0.01 mg/kg once daily) as adjunctive therapy after shock wave lithotripsy in addition to paracetamol while group 2 received paracetamol only. Stone clearance was defined as no renal stone fragments or fragments less than 3 mm and no pelvicalyceal system dilatation. Results: Our study included 69 boys and 51 girls with a median age of 3.5 years and a median stone size of 1.2 cm. There was no statistically significant difference between groups 1 and 2 in stone or patient criteria. Of the children 99 (82.5%) achieved stone clearance after the first session, including 50 in group 1 and 49 in group 2. All children in each group were cleared of stones after the second session. The overall complication rate was 14.2%. There was no statistically significant difference between single session stone clearance rates (p ¼ 0.81) and complications rates (p ¼ 0.432) in either group. On multivariate analysis using logistic regression smaller stone size (p ¼ 0.016) and radiopaque stones (p ¼ 0.019) were the only predictors of stone clearance at a single shock wave lithotripsy session. Tamsulosin therapy did not affect stone clearance (p ¼ 0.649). Conclusions: Tamsulosin does not seem to improve renal stone clearance. Smaller and radiopaque renal stones have more chance of clearance after shock wave lithotripsy for pediatric single renal pelvic stones.NULL