Most clinicians only have a limited experience in treating childhood hypercalcemia with bisphosphonates. We report our experience in the use of intravenous and oral bisphosphonates in a 5-year-old with hypercalcemia secondary to acute lymphocytic leukemia, a 16-year-old with immobilization hypercalcemia, and a 14-year-old with chronic hypercalcemia of unknown cause. Single infusions of 0.5 mg/kg and 1 mg/kg of intravenous pamidronate were administered over 4 hours. No adverse reactions were observed except for hypocalcemia. A dose between 10 and 20 mg of oral alendronate was successfully used to maintain normocalcemia in the patient with chronic hypercalcemia. In our experience, the administration of bisphosphonates has enabled us to achieve normocalcemia in all cases, and in all cases there were no significant side effects. Long-term potential side effects from their use in children during the active phase of growth remain unknown. Pediatrics 1998;102:990-993.