Abstract: Objective To investigate the pathologic characteristics, clinic manifestations, diagnosis and treatment of congenital hydronephrosis caused by ureteropelvic junction obstruction(UPJO) in children. Methods 1 376 children( male 1 169 and female 207, left side in 894, right side in 309 and bilateral in 173) with UPJO were treated in our hospital during the last 50 years,including 1 279 Anderson-Hynes and 97 Y-V procedures. Results All patients were followed up for at least 6 months. Congenital hydronephrosis are most commonly caused by ureteropelvic junction stenosis(94.3%), upper ureteral valve, upper ureteral polyps and an aberrant, accessory or early branching vessel to the lower pole of the kidney as well. Conclusion The most common cause of ureteropelvic junction obstruction is ureteropelvic junction stenosis. Anderson-Hynes procedure should be applied to children with obstructive symptoms and ultimately damaged renal function.

Key words: congenital anomalies, hydronephrosis, pathology