A 67-year-old man was hospitalized with the chief complaint of diffuse abdominal pain for 3 days. Hypercalcemia and acute pancreatitis was found by laboratory examination. Abdominal CT scans showed swelling of the pancreas, multiple liver tumors and osteolytic lesions of bone. Upper mediastinal lobulated mass was suspected from chest x-ray examination, then small cell lung cancer (SCLC) was proved by bronchoscopic and pathological examination. The final diagnosis is SCLC with liver and bone metastasis associated with hypercalcemia and acute pancreatitis. After pancreatitis subsided, the patient was put on chemotherapy. Unfortunately, due to immunocompromise, he died of pneumonia and sepsis. There was no reasonable explanation regarding to the cause of acute pancreatitis except hypercalcemia, which might be due to SCLC with bone metastasis. This is the first report of such a complication in a patient with SCLC.