Noninvasive, pulsed electromagnetic field treatment, when properly employed, was effective in securing healing of ununited fractures in 64.4% of 149 patients. The effectiveness of this modality can be ascertained after three months of intensive use in more than 85% of patients, thus enabling the clinician to decide to terminate treatment, continue electrostimulation, or abandon it in favor of another treatment modality. The success of treatment is dependent upon certain variables. Anatomic location of the nonunion is important. Higher healing rates were noted in the tibia than in the femur or humerus. In some conditions, combined electrostimulation and bone grafting was more effective than either measure alone. Young patients healed more rapidly than older patients. Electrostimulation is more effective when instituted within two years of the original fracture than when started at longer intervals after the injury. Infection, either quiescent or actively draining, does not seem to affect the overall results. Of greatest importance is patient adherence to the treatment protocol as outlined, with emphasis placed on adequate immobilization of the fracture and absolute nonweight-bearing during treatment. Considering these factors and in light of the very rare frequency of short-term side effects, the use of pulsed electromagnetic fields appears to be a reasonable choice of treatment in the management of ununited fractures.