Introduction: To achieve an appropriate treatment for low back pain we should know the exact reason of the pain. Beside physical examination, imaging modalities like CT scan and MRI are the other diagnostic methods for LBP. Furthermore, electrodiagnostic studies help to diagnose the reason behind radiculopathy. Actually when the reason of radiculopathy is unclear, these methods help to localize the exact nerve root causing the pain and rule out the similar reasons of radiculopathy. The aim of this study was to compare MRI and EMG in diagnosing the reason of lumbosacral radiculopathies. Methods: In this cross sectional descriptive-analytical study, the number of patients who came to neurosurgery clinics with LBP and lumbar discopathy and been evaluated by MRI and EMG were studied. Later, for every patient a questionnaire was completed based on the results achieved from MRI and EMG and the obtained results were compared. Results: 100 patients were participated in this study, 60% female and 40% male. The average age of patients was 39/75 years. The most frequent chief complaint of patients was LBP with a prevalence of 43%. MRI findings showed 64% involvement of L4/L5 level in these patients. On the other hand, EMG findings also showed L4/L5 level involvement in 64% of patients confirming the hypothesis of our study that MRI and EMG findings are compatible with each other in determining the level and intensity of disc involvement. Conclusion: For determining the level of injury in lumbosacral radiculopathies, both MRI and EMG are equally useful. Additionally, in borderline cases we can use EMG to confirm MRI findings to determine the intensity and level of injury. Keywords: Lumbosacral radiculopathy; Magnetic Resonance Imaging; Electromyography