Background: Low back pain (LBP) is associated with abnormal spinal posture (lumbar hypo-/hyper-lordosis).Radiographic method (X-ray) is costly and risky. Therefore, testing the validity of safer and cheaper methods such as inclinometer is needed due to lack of research. Purpose: to test the validity of inclinometric method compared toradiographic one in measuring lumbar curvature. Methods: This diagnostic accuracy study included thirty-one patients of both genders complained from LBP with mean age of 40.4 years.They were categorized into two groups; group A included 18 patients whom lumbar lordotic angle (LLA) was measured with inclinometer and group B included 13 patients whom LLA was measured by Cobb, s angle (on plain X-ray sagittal views). Results: There was no significant differences between LLA measured by radiographic and inclinometric methods (MD=5, P-value= 0.082). Conclusion: Measuring LLA with inclinometer is valid compared to radiographic method in patients with LBP. Inclinometer is cheap, usable, and accessible in both research and clinical setting.