Background: Humoral hypercalcemia of malignancy (HHM) is rarely reported in the patients with cholangiocellular carcinoma (CCC), usually occurring weeks to months prior to the patient`s death. Case 1: A 63-year-old male was admitted for the liver mass evaluation. The initial blood test showed hypercalcemia (12.0 mg/dL). Computed tomography (CT) scan and subsequent liver biopsy confirmed 13cm unresectable cholangiocarcinoma and he was treated chemoconcurrent radiotherapy with capectabine and cisplatin. As the tumor showed marked responsek, the serum calcium level was decreased to the normal range. But, when disease progression was found by the follow up CT, hypercalcemia redeveloped with suppressed parathyroid hormone (PTH) level and elevated parathyroid hormone related peptide (PTH-rP) level. We treated the patient with intravenous hydration and pamidronate and started second line chemotherapy with gemcitabine. After two cycles of gemcitabine, disease progression was revealed. He is still surviving after 11 months of initial diagnosis with HHM. Case 2: A 68-year old male presented with the weight loss and abdominal pain. CT scan and liver biopsy confirmed cholangiocarcinoma with innumerable liver to liver metastasis and node metastasis. He received palliative chemotherapy, gemcitabine plus cisplatin. His tumor was controlled in a stable status until when 8th cycle of gemcitabine and cisplatin. At that time, his blood test showed serum calcium of 11.7 mg/dL. After he was treated with hydration and intravenous pamidronate, he returned home. When he visited outpatient clinic one week later, hypercalcemia was aggravated (13.2 mg/dL) with suppressed PTH and increased PTH-rP. CT scan and tumor marker revealed the marked progression of disease. He was hospitalized and treated with intravenous hydration and pamidronate. Considering poor performance, we discontinued chemotherapy for him and treat him only with best supportive care. Conclusion: We present two first cases in Korea of HHM associated with CCC. Especially the first case is of note in that it demonstrates the strong correlation of hypercalcemia with the disease burden and response of hypercalcemia to cancer treatment.