PURPOSE : The purpose of this study is to evaluate the seg length discrepancy after Ender nail fixation in children's femoral shaft fracture. MATERIALS AND METHODS : We reviewed 18 femoral shaft fracture that were treated with Ender nail and studied the relationship between the initial site of fracture, type of fracture and overgrowth. The age of children in this study ranged 6 to 13 years old and the average period of follow-up was 32 months. RESULTS : The range of leg length discrepancy was from 6 mm shortening to 16mm lengthening and average 3.4 mm lengthening. Only one patient had shortening, nine patients had limbs of equal length(less than 2 mm) and eight patients had lengthening. The average overgrowth was 1.3 mm in proximal 1/3, 7.0 mm in middle 1/3, 3.0 mm in distal 3/1 fractures. The average overgrowth was 7.3 mm in transverse, 1.3 mm in oblique and 2.3 mm in comminuted fractures. Conclusions : We consider closed Ender nailing in children femoral shaft fractures as a good treatment modality in the matter of leg length discrepancy.