Nonunions of long bone fractures can be treated successfully with one operative procedure in more than 90% of patients. In fact, 80% of patients can have good to excellent final restoration of mechanical axis alignment and proper length. Patients with infected nonunions may require more than one procedure to eliminate infection and heal the nonunion. Treatment must be tailored to the individual patient to address all components of the problem. We reviewed the main experimental data regarding the knowledge of nonunions and the basic methods that may be applied to the treatment of nonunions.