A 12-year-old girl was admitted to our hospital with signs of an acute abdomen with paralytic ileus. The previous and family history were without abnormalities. Abdominal pain and vomiting had started two days earlier. On palpation the swollen abdomen was painful and there was an increased tension in the left upper part. The clinical diagnosis of acute pancreatitis was confirmed by an increased serum level of lipase (4480 U/l). Clinical chemical investigations further revealed a permanent hypercalcemia in the range of 6.4 to 8.3 mval/l. This, together with concomitantly reduced levels of serum phosphate and a threefold increased level of parathyroid hormone (343 pg/ml, upper limit of reference = 100 pg/ml) were consistent with a hyperparathyroidism. In fact, sonography of the cervical organs revealed a solitary adenoma of the parathyroid glands. After surgery serum levels of calcium returned to normal. Hypercalcemia as a consequence of primary hyperparathyroidism has to be included in the differential diagnosis of acute pancreatitis in childhood.