During the past year, investigations involving the etiology, diagnostic evaluation, and therapy of low back pain have reported interesting new data. The natural history of degenerative intervertebral disk disease may be explained by peripheral annular fiber injury that results in damage to the nucleus pulposus. Diurnal changes in patient clinical symptoms and signs may have a correlate in alteration of spinal mechanics that occurs during the course of a day. The diagnostic evaluation of low back pain continues to be revolutionized by magnetic resonance imaging. Although magnetic resonance imaging is able to detect specific lesions with greater sensitivity than other radiographic techniques, correlation between clinical symptoms and signs and anatomic abnormalities is essential for correct diagnosis. Therapeutic controversies continue concerning the efficacy of chiropractic intervention and transcutaneous electric nerve stimulation for low back pain patients. Microsurgical techniques for disk removal may prove to be associated with less morbidity than diskectomy with laminectomy, but require additional study.