Primary hyperparathyroidism, a genetically heterogeneous disease, usually occurs as a sporadic disorder due to the presence of parathyroid adenoma/s, hyperplasia or, rarely, carcinoma. In the last decades familial forms of primary hyperparathyroidism have been described. Recognizing such forms is essential for a correct clinical management of affected individual subjects and families. In fact, primary hyperparathyroidism may be the typical feature of familial syndrome or alternatively only an associated disorder within the context of a more complex syndromic picture. Several responsible genes have been so far identified, making their mutational analysis possible, which provides not only early identification of asymptomatic gene carriers, but could also add new important knowledge of the molecular mechanisms underlying parathyroid tumorigenesis. Such mechanisms could, in the near future, become an ideal target for new therapeutic strategies of primary hyperparathyroidism.