Twenty-one skeletally immature patients between 11 and 16 years of age were treated operatively for a unilateral femoral shaft fracture. Eleven patients underwent fixation with flexible nails and 10 with rigid nails. The patients were studied retrospectively to determine the similarity of the groups. Each method of fixation was then compared to determine the technical ease and final outcome. Both methods gave excellent final radiographic alignment with minimal complications. Flexible nailing required much less operative time and less fluoroscopy time. Estimated cost of using Ender nails is much less than using Russell-Taylor interlocking nails.