At the Innsbruck Trauma Department a total of 75 children with closed femoral shaft fractures were reviewed with reference to length discrepancy. The femurs were measured radiologically two times within four years to find out, if overriding of the fragments is useful to prevent overgrowth of the broken limb. In 60 patients conservative treatment and in 15 cases operative treatment was performed. The cases may be divided in two age groups: one ten years of age or younger, the other eleven years to 15 years. Shortening of the fragments shows no evident advantage preventing overgrowth of the broken limb, but in elder children it may provoke a persisting shortening of the limb. As a matter of fact anatomical reduction in conservative treatment of femoral shaft fractures, especially in elder children, should be performed. After operative treatment the children ten years of age to 15 years showed not even more lengthening of the femur than the patients with conservative treatment.