Based on the author's experience with more than 20 cases of immobilization hypercalcemia following spinal cord injury, current concepts of this condition are presented. Symptoms may be mild or severe: laboratory findings are essential for differential diagnosis in older individuals, in whom preinjury Paget's disease and mild primary hyperparathyroidism must be ruled out. Most cases of immobilization hypercalcemia are seen in adolescent boys following recent spinal cord injury. Besides sex (male), risk factors include age (less than 21 years), complete neurologic injuries, high cervical levels of spinal cord injury, dehydration, and a prolonged period of immobilization. A preinjury history of large ingestion of milk and/or extreme exposure to sunshine may also be contributory factors. Therapy includes vigorous hydration, saline infusions and diuretics, calcitonin, and steroids. The clinical course, without treatment, may be prolonged to 14 months, but the condition is always self-limiting.