An 18-yr-old boy presented with extreme back pain as the result of multiple vertebral fractures. At age 16 he had developed a tumor of the mesencephalon. A ventriculoperitoneal shunt was established surgically. One year later, he developed progressive neurologic deficits in his upper and lower limbs with an increase in the size of the tumor. He was treated by irradiation and high doses of glucocorticoids. Although the neurologic deficits progressively improved, he developed severe back pain resulting in complete immobilization for 3 mo in spite of neurologic recovery. Multiple vertebral fractures were diagnosed by X-ray. Bone density was extremely low (Z-score of -5.5 in the spine and -3.1 in the femoral neck). The patient was treated with calcium and vitamin D, calcitonin, bisphosphonates, physiotherapy, and progressive mobilization. Glucocorticoids were decreased and could be stopped as the neurologic deficits fully recovered. After 1 yr of treatment with intermittent i.v. pamidronate, bone density had increased by 40% in the spine and by 25% in the femoral neck despite growth arrest. He progressively recovered from back pain and is now, at age 20, fully ambulant, studying mechanical engineering, without neurologic sequelaes and free of glucocorticoids. Magnetic resonance imaging revealed that the tumor had disappeared. This case proves that treatment of symptomatic glucocorticoid-induced osteoporosis during puberty can be rewarding, even when multiple and invalidating vertebral fractures already exist.