We report a patient with medulloblastoma showing severe hypercalcemia and a raised PTHrP serum level. He was a 19-year-old with a history of recurrent medulloblastoma. He developed constipation, lethargy and altered mentality for 3 weeks. There was no family history of hypercalcemia. Laboratory test revealed hypercalcemia of 18.2 mg/dL . PTHrP increased to 10.7 pmol/L (normal range: 1.1 pmol/L), whereas serum level of intact parathyroid hormone was suppressed to 5 pg/mL (normal range: 15-65 pg/mL). Intoxications of 25-hydroxy-vitamin D3 and 1,25-dihydroxy vitamin D3 were also excluded. After the diagnosis of humoral hypercalcemia was made, single dose of intravenous pamidronate (1mg/kg) was injected to patient with massive hydration. After 3 days, level of serum calcium was normalized. After 7 days hypocalcemia which was one of the complications of bisphosphnates developed. Although long-term efficacy and safety data are insufficient, bisphosphonates can be effective treatment for humoral hypercalcemia associated with malignancy.