Back pain patients have restricted spinal movements, and the pattern of disturbance from normal movements may indicate the pathology and the functioning of the lumbar spine. Biplanar radiography was used to measure the three-dimensional intervertebral movements of patients with back pain alone and with back pain plus nerve tension signs demonstrated by restricted straight leg raise. Statistically significant decreases in flexion/extension compared with a normal control group were demonstrated for both groups. Accompanying coupled movements were increased only in those patients without nerve tension signs indicating asymmetrical muscle action, while those with tension signs had symmetric splinting particularly of the lower levels. Conservative treatments had no effect either clinically or on the movements. Caudal epidural injections produced clinical improvement and increased movements demonstrating relaxation of muscle splinting. Biplanar radiography, although capable of differentiating between the groups was not able to provide clinically useful information concerning individual patients with this type of back pain.