Low back pain arising from the apophyseal joints of the thoracolumbar region is common and is often erroneously attributed to pathologic changes in the low back. The diagnosis is made on pure clinical grounds. Classic signs are: a positive "iliac-crest point" test, a positive skin-rolling test, localized tenderness over a certain spinous process at the thoracolumbar junction and tenderness over the involved apophyseal joint. The diagnosis is confirmed by a periapophyseal joint block using a local anesthetic. Of 350 patients seen in a back pain clinic, 40% were found to have pain of thoracolumbar origin. Treatment included manipulation, infiltration with corticosteroids, electrocoagulation and/or surgical denervation of the involved apophyseal joint.