Laparoscopic dismembered pyeloplasty for ureteropelvic junction (UPJ) obstruction is considered to be a routine procedure in many pediatric surgical centers. UPJ obstruction is known to be associated with horseshoe kidney and several reports on successful laparoscopic repair in such cases exist. The case of a 9-month-old girl with Turner syndrome is reported. A horseshoe kidney with grade 4 hydronephrosis on the left side was diagnosed by ultrasound during the neonatal period. MAG3 diuretic renography and dynamic magnetic resonance imaging nephrography revealed a differential renal function of 31% and 69% on the left and right side, respectively.