We present a case of parathyroid adenoma resulting in hypercalcemic crisis with lethal outcome and subsequential autopsy findings pointing out to long term hypercalcemia. A 51- year-old female was admitted to hospital due to vomiting, constipation, general weakness, hypotension and uncorrectable hypokalemia. A couple of hours after the admission her general appearance deteriorated and she became disoriented, more pale and developed both eye blindness. Laboratory findings revealed leukocytosis, increased values of urea, hypokalemia, thrombocytopenia, high blood calcium (26 mg/dL) pointing out to hypercalcemic crisis. Hypercalcemia was immediately treated, but unsuccessfully leading to lethal outcome. Autopsy revealed presence of pulmonary oedema, ascites, acute pancreatitis, diffuse calcification of arteries, bone osteopenia, left pulmonary artery thromboembolism, heart hypertrophy and nodule under the right thyroid lobe which was later pathohistologically described as parathyroid adenoma. Presence of chronic hypercalcemia due to parathyroid adenoma is difficult to be recognized since most cases are asymptomatic, but it is necessary in order to avoid chronic complications of calcium deposition and possible development of hypercalcemic crisis which is life threatening condition demanding immediate treatment.