The occurrence of acute pancreatitis secondary to primary hyperparathyroidism-induced hypercalcemia is a rare condition. The common causes of primary hyperparathyroidism are parathyroid adenoma and hyperplasia, accounting for 95% of all cases. Rare causes include parathyroid cancer and cysts. To our knowledge, the parathyroid cyst presenting as acute pancreatitis has not been reported previously in Korea. Herein, we report a case of acute pancreatitis caused by parathyroid cyst and review the literature pertaining to this condition. A 67 year-old male was admitted to our hospital with a 2-day of epigastric pain. There was no previous history of peptic ulcer disease, cholecystitis with gallstones, any alcohol ingestion, or abdominal surgery. Laboratory studies revealed a white blood cell count of 9000/mm3 (normal 6000-10,000), hemoglobin 15.7 g/dL (normal 12-16), platelet count 135000/mm3 (normal 130,000-450,000), serum albumin 4.4 g/dL (normal 3.0-5.0), aspartate aminotransferase 29 U/L (normal 5-37), alanine aminotransferase 29 U/L (normal 5-40), alkaline phosphatase 84 U/L (normal 39-117), g-glutamyl transpeptidase 148 U/L (normal 7-49). Serum amylase and lipase were 293 U/L (normal 20-90), 660 U/L (normal 7-60), respectively. Serum triglyceride was 93 mg/dL (normal 50-200). Total calcium was 5.15 mEq/L (normal 4.2-5.1) with 2.8 mEq/L, ionized fraction (normal 2-2.4). Inorganic phosphate was 1.9mg/dL (normal 2.5-5.5). An abdominal CT revealed mild swelling of the pancreatic head with peripancreatic infiltration . He underwent conservative treatment for acute pancreatitis. As epigastric pain was improved, serum ionized calcium rised to 3.0 mEq/dL and serum parathyroid hormone level was 113 pg/mL (normal 9-55). Neck CT showed a 4.6 cm sized cystic lesion in left infrathyroidal area extending to mediastinum. This cystic lesion was surgically removed. The surgical specimen was interpreted as parathyroid cyst. After operation, serum calcium and phosphate levels were normalized. At follow-up examination, he has remained asymptomatic.