The sequence of events occurring after fracture is now relatively well understood. Healing takes place in three phases--inflammatory, reparative and remodelling. In each phase certain cells predominate and specific histologic and biochemical events are characteristic. Factors that influence fracture healing are both local and systemic; the former include particularly the degree of local trauma and bone loss, the type of bone affected, the degree of immobilization and local pathologic conditions; the latter include age, hormones, local stress and electric currents. Natural processes of healing should be allowed to take their usual course and interference should be attempted only when there is demonstrable need or substantial advantages for the patient.