Background: The most common orthopedic injury necessitating hospitalization in children is femoral fractures(1).The American Academy of Orthopedic Surgeons recommends that clinicians consider using flexible intramedullary nailing for treatment of children aged 5 to 11 years having diaphyseal femur fractures ( level of Evidence: III ,Grade of Recommendation: C ). Antegrade placement of "C"-shaped and "S"-shaped nails, retrograde placement of 2 "C"-shaped nails (CC) through medial and lateral approaches, and retrograde placement of "C"-shaped and "S"-shaped nails (CS) through a single lateral approach are all nail configurations for flexible intramedullary nailing (FIMN).(2) Objectives: The aim of this study was to evaluate the clinical and radiological results of paired CS flexible nails placed in retrograde manner for the treatment of pediatric femoral shaft fractures Patients and methods: This study included 20 child aged from 5 to 12 years old with diaphyseal fracture femur treated by flexible intramedullary nailing (FIMN) in Helwan University and Sheikh Zayed specialized hospitals. The results were assessed at the end of follow up clinically using Flynn’s score and radiographically by plain radiographs. Results: They were 6 females (30 %) and 14 males (70 %). Their ages ranged between 6 to 12 years with a mean of 7.67 ±2.34 years. The duration of anesthesia in this study was 45 minutes. In this study, postoperatively, 14% of patients had no pain (VAS = 0), 30% had mild pain. Conclusion: CS retrograde fixation technique for flexible nails provide excellent clinical, radiological outcomes and a low complication rate for the treatment of pediatric femur fractures. The CS technique can be a fast operation, but proper technique is critical to minimize shortening and malunion of pediatric femoral fractures.