The authors reviewed the diagnostic use of clinical findings on physical examination, electrodiagnostic data, and radiologic findings including magnetic resonance imaging (MRI) in 55 patients with low back pain (LBP). Radiologic parameters included the lumbar lordosis, lumbosacral joint angle, and disc height narrowing. Clinical parameters included straight leg raising test, motor and sensory tests, and deep tendon reflxes (DTRs) on physical examination. MRI findings were classified 6 categories as bulging, protruded, extruded, sequestered, normal, and multiple level. In 35 cases of radiculopathy group, the severity of herniated intervertebral disc was well correlated with some of clinical and radiologic parameters, such as motor weakness, sensory or DTR abnormalities, and L5/S1 disc height. There was no correlations between MRI and electrodiagnostic findings on the site of the root lesions in all but 10 cases(18.2%). We suggest that the electrodiagnostic studies should be performed routinely as part of LBP evaluation for the identification of site and degree of radiculopathy.