Management of nonunions requires careful and critical assessment of the true biologic status of the fracture. The mere radiographic persistence of a fracture line does not invariably indicate nonunion. Ten percent of fractures considered initially to be ununited in this series healed spontaneously without further treatment. The patient who has no pain with weight-bearing and no demonstrable motion on careful stress studies does not usually require further treatment, except for protection against reinjury. Intraosseous venography may be useful to distinguish the delayed from the nonunion in order to institute appropriate and early treatment. Percutaneous direct-current electrostimulation is proving to be a reliable and effective method of managing the most common nonunion of the tibia or distal femur. It appears less satisfactory for the more proximal femoral fractures and for fractures of the humerus. Electrical stimulation does not eliminate the need to stabilize the nonunion of either the femur or the upper limb. Electrical stimulation also does not eliminate the need for bone grafting in approximately 15% to 20% of nonunions. The fractures' biologic inability to respond may be identifiable by 99MTc diphosphonate bone scan. The implantable direct-current electrical stimulatory device proved ineffective in this series. Hopefully, further development of this technology may produce more consistent results in the future. The electromagnetic noninvasive stimulator appears to be a useful alternative method to the semi-invasive system. This, of course, should depend on the individual needs of the patient and the nature and location of the fracture. Continued technologic improvement in all electrical stimulatory methods should broaden their usefulness and applicability. However, the healing status of the fracture and the processes by which each fracture responds must be carefully assessed to appreciate what is being effected by electrical stimulation. Critical evaluation and clarification of indications are essential if the patient is to be offered the most effective therapy available.