When treating femur shaft fracture in adults, undreamed nail can be an option in order to avoid systemic complications. To appropriately insert unreamed intramedullary nail, an accurate entry point and sufficient reaming of the entry portal is essential. The intramedullary canal of the proximal femur must be reamed over than the diameter of the proximal end of the nail. If the proximal reaming is not sufficient, complications such as bursting fracture of proximal femur can occur. We present two cases of bursting fracture of proximal femur following insertion of undreamed intramedullary nail as well as a literature review.