Proliferative processes of the parathyroid gland cause hyperparathyrosis (HP), Primary HP-s (carcinoma, adenoma, hyperplasia) are characterised by absence of feedback to seCa level. Out of estimated 2040/100 000 cases of hypercalcemia (HC), mainly due to HP, only 25% becomes detected. The relative incidence of parythyroid carcinoma (PCc) among causes of HC is 12%, but the highest seCa and parathormone (PH) levels are caused by PCc. Clinical diagnosis of PCc is based on palpable mass, seCa above 14 mg/dl, decreased seP, increased serum alkaline phosphatase, urine Ca and 310 times increased PH level. Renal calculi, renal calcinosis, osteoporosis and Engel-Recklinghausens disease (1%) develop and may be the first symptoms of PCc. Nearly all imaging methods, including Tc99-labelled radiopharmacon scan are used in localisation of PCc. The diameter of PCc may reach or exceed 3 cm. PCc has rich stroma, causing lobulation. Cellular polymorphism is usually present, but mitotic and also apoptotic ratio is relatively low. Infiltrative growth, vascular invasion and metastatic spread (lymph nodes, lung, liver, bones) ensure diagnosis of malignancy. Recurrance rate is 4060%, 10 years postoperative survival is 77%. Literary data and our studies show balance between pro- and anti-apoptotic genes in hyperplasia and adenoma, some similarities between normal parathyroid tissue and PCc. Overexpression of Ki67, MIB1, Galectin3,apollon, underexpression of RB, parafibromin, p27, bcl2, flip, cyclinD1 and ck8 are valuable signs in favour for diagnosis of PCc. Etiology of PCc is still uncertain. Data on heredity, especially on gene mutation of HRPT2, underexpressing parafibromin and consequently cyclinD1 may lead to better understanding pathogenesis of PCc. Primary therapy of PCc should be surgical. To avoid consequences of HC, bisphosphonates, Ca sensor receptor blocking calcimimetics, Gallium nitrate, calcitonin, Vitamin D1 analogs are recommended. Gene therapy is in experimental phase.