Introduction: Muscle injuries are common and may be associated with impaired functional capacity, especially among athletes. The results of healing with conventional therapy are often inadequate, generating substantial interest in the potential for emerging technologies such as stem cells to enhance the process of soft tissue healing and to decrease time of recovery. Aim of the Work: Evaluation  the role of BM-MSCs in healing of experimentally induced skeletal muscle injury in adult male albino rat.Materials and Methods: Forty-five adult male albino rats were used. They were divided into five groups. Group I: bone marrow was taken from both femur and tibia to prepare stem cells and the gastrocnemius muscle was obtained. Group II: gastrocnemius muscle was injured and specimens were taken at the same day within 6 hours. Group III: gastrocnemius muscle was injured and left without treatment. Group IV: gastrocnemius muscle was injured and immediately treated by intramuscular injection of stem cells. Group V: gastrocnemius muscle was injured and immediately treated by intramuscular injection of media used for suspension of bone marrow. Muscle specimens were excised from group III to V after 2 weeks and 4 weeks from injury and used for histological and electron microscopic study. Results: The results revealed that stem cell treated group showed early and enhanced regeneration of skeletal muscle injury. This was evidenced by light and electron microscope and morphometric study. The stem cell treated group demonstrated early formation of many myotubes 2 weeks after injury and ultrastructural features of activated satellite cells in association with restoration of normal histological features of muscle fibers without fibrosis. Conclusion: It could be concluded that a local injection of stem cells into the injured gastrocnemius muscle resulted in early activation, proliferation and differentiation of satellite cells and accelerated muscle healing.