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. Nonunion is a serious complication of a fracture, occurring in 2-10% of patients, as it is associated with high economic and health burden. Many cases are subsequently approached by multiple surgical and nonsurgical modalities. Various devices, under the name of "bone growth stimulators" have been used to enhance healing of the fracture. Recent studies, demonstrated the efficacy of mesenchymal stem cells in regeneration of bone and cartilage tissue. In this study percutaneous injection of mesenchymal stem cells to the site of fracture is performed as an outpatient procedure or during an operative exposure to evaluate its efficacy in enhancing bone regeneration. In the case of small size of bone gap, mesenchymal stem cells are injected into the callus of fracture site through an outpatient procedure under the guide of fluoroscopy. If there is a large bone gap, through a surgical management, mesenchymal stem cells seeded on bone matrix are placed at the site of fracture. Patients are followed by X-Ray examination 1,2,6, and 12 months after treatment.