Treatment of nonunion, delayed union and malunion fractures of long bones remains problematic. The definition of nonunion is a failure of the fracture to heal in six months in a patient in whom progressive repair had not been observed radiographically between the third and sixth month after the fracture. First of all good surgical techniques are stable immobilization must be obtained and local sepsis excluded. Then stimulation of the callus is required. Numerous techniques have been developed ranging from invasive interventions (including internal fixation with the use of bone graft or bone graft substitutes) to non invasive procedures (ultrasound and pulsed electromagnetic fields).