The neurologic manifestations of Paget disease and the therapeutic effect of calcitonin were studied in 49 patients. Twenty-four patients (49 percent) had neurologic disorders involving cranial nerves other than the auditory system, brainstem, spinal cord, or spinal roots and nerves. Eighteen of the 24 patients (75 percent) showed significant subjective or objective improvement after calcitonin treatment. The effect of calcitonin treatment on spinal cord compression was dramatic in three of six patients. The observations made of these patients support previous data suggesting that the neurologic signs and symptoms of Paget disease have their pathogenesis in both mechanical impingement and vascular distortion. The importance of early detection of neurologic signs and symptoms is emphasized, since prompt treatment with calcitonin may prevent severe complications.