Paget's disease of bone is most commonly seen in the spine; it may either be asymptomatic or may cause pain and neurologic impairment. We describe a patient with back pain due to Paget's disease of the second lumbar vertebra and spinal stenosis. The patient had a dramatic clinical and radiographic response to 2 courses of etidronate disodium, which was evidenced by resolution of the back pain and improvement in bony spinal stenosis. Etidronate may be effective in reversing bony spinal stenosis due to Paget's disease.