The authors present their experience related to extreme complications in treatment of diaphyseal fractures of the long bones with application of the Fixion expansion intramedullary nail in a total of 48 surgeries. We have encountered six (12.5%) extreme complications in the management of fractures of 3 humeral, 2 tibial, and 1 femoral bones during its application procedure and postoperative follow-up. Of six cases, two with humeral and tibial fractures developed nonunion and rotational instability because of failure of inflation of the Fixion nail. One of the Fixion nail in humerus was broken spontaneously, and one of the Fixion nail deflated at the follow-up and pseudoarthrosis developed in this patient. In a patient with osteogenesis imperfecta, during the inflation of the nail for the treatment of femur fracture, a new longitudinal fracture occurred and conventional non-locking intramedullary nail was inserted. In a patient with a tibia fracture that was treated with the Fixion nail, new fracture occurred due to its bending after weight bearing in the postoperative period. The Fixion nail application is a new technique for the intramedullar fixation of long bones. It is considered as an effective method for the selective fracture types of long bones. Application may need special training. Since the Fixion has not got rotational stability and rigidity as conventional nailing systems, bending and breaking of the nail may occur during postoperative period in patients with over obesity and hyperactivity. In patients with osteogenesis imperfecta, it may not be the first choice as a nailing system.