Primary hyperparathyroidism (PHPT) during pregnancy is a rare, but may cause many maternal and fetal complications. Most cases are mild and very often remain undiagnosed throughout the whole pregnancy period, especially since its symptoms overlap those occurring in normal pregnancy. Additionally, physiological changes in calcium metabolism and PTH secretion may make the diagnosis difficult. Some current data indicate, that in pregnant women with mild PHPT the risk of obstetrical complications do not increase. However, according to others some complications, including miscarriage, intrauterine growth retardation or preeclampsia continue to occur even in subjects with mild hypercalcemia or those previously successfully treated for PHPT. Additionally, the course of PHPT during pregnancy may exacerbate, and rapid severe worsening of hypercalcemia may occur in the postpartum period. Parathyroidectomy, optimally performed during the second trimester, remains the main and the only definite treatment of PHPT, especially, when the serum calcium level exceeds 2,75 mmol/l. In patients with mild, asymptomatic PHPT some experts recommend conservative treatment with postponing surgery to the postpartum period. There are no medical guidelines regarding the treatment of PHPT during pregnancy. Therefore, to achieve optimal care of pregnant women with PHPT, they should be diagnosed, monitored and treated in reference centers by multidisciplinary teams of closely cooperating specialists. Conservative treatment is possible only on condition of close monitoring of the mother and child during pregnancy and after delivery.