Background: Muscle injuries are extremely common and may have a profound effect on the individual presenting with them. Determination of the severity of injury to the soft tissues is an important component of patient assessment and affects management of closed fractures. Aim of Study:To assess muscle injury associated with upper and lower closed limb fracture using ultrasound, and to develop ultrasound classification criteria for muscle injury.Patients and Methods: This study is a prospective observational study, was conducted on 30 patients with closed limb fracture and muscle injury at Diagnostic Radiology Department, Ain Shams Hospitals, through of 3 months. Result:The mean size of muscle hematoma was 25.16 ± 6.99mm with range from 15mm to 36mm. The hematoma showed a honeycombed pattern in 3 (10%) cases. Conclusion:Ultrasonography is useful for diagnosing acute muscle injury associated with limb fracture. The ultrasound classification criteria for muscle injury can be used to predict the severity of injury and guide decision on the type of treatment. However, the criteria need to be verified on a larger sample of patients, and some sections of the proposed criteria may require a more detailed analysis.