Background: Spinal deformity is common among the general population; it affects about 27.3% of all deformities related to musculoskeletal system which progressed over time and exerts significant effect on the health-related quality of life. Assessment of spinal deformities almost depends on radiological methods with no respect to their harmful effect. Spinal Mouse (SM) is radiation free device used for assessment of spinal deformities, segmental and global range of motion of spine. Aim of the study: To investigate the concurrent validity of spinal mouse device in assessing sagittal plane deviation in both thoracic and lumbar regions. Methods: Fifty-five patients diagnosed with lumbar spondylosis participated in the study. Their ages ranged from 40-60 years. All subjects were evaluated clinically and radiologically. The examiner performed assessments using spinal mouse and took a radiological film to measure the sagittal spinal deviations either kyphosis in thoracic region or hyper or hypo-lordosis in the lumbar region. Results: There was significant correlation between measures of thoracic spinal deformity using both spinal mouse and X ray methods (p =0.001), (r= 0.918). There was a significant correlation between measures of lumbar spinal deformity using both spinal mouse and X ray methods (p =0.000), (r= 0.827). Conclusion: Spinal mouse was a valid device used for measurement of thoracic and lumbar spinal deformity in sagittal plane with no harmful effect especially in individuals with lumbar spondylosis and spinal deviations that need regular assessment and follow up.