Parathyroid cancer is a rare endocrine malignancy, representing less than 1 % of all cases of primary hyperparathyroidism. The exact etiology of the disease remains unknown. Known risk factors include neck irradiation, end stage renal failure, genetic factors, particularly the the HPRT2/CDCT73 gene mutation. The clinical picture is often indolent, yet progressive with a trend of local invasion and metastasis formation in advanced disease. The clinical picture includes symptoms of severe and resistant hypercalcemia, requiring intensive therapy often with the need of dialysis. Radical surgery is the mainstay of the parathyroid cancer treatment. Chemotherapy and radiotherapy are generally ineffective. An early and correct diagnosis of parathyroid carcinoma significantly influences both morbidity and mortality.Key words: diagnosis - hyperparathyroidism - parathyroid cancer - treatment.