We report a case of primary Hyperparathyroidism (HPT) occuring in a 36 year old woman, during pregnancy. This woman received medical therapy to the delivery, then underwent parathyroidectomy in post-partum. Primary HPT during pregnancy is associated with increased risk of fetal loss, neonatal and maternal morbidity. Neonatal hypocalcemia is due to transient hypoparathyroidism consequent to abnormal suppression of fetal parathyroid hormone secretion by maternal hypercalcemia. Maternal hypercalcemia may be masked by hypoalbuminemia during pregnancy and often leads to aspecific symptoms which will differ the diagnosis. The recommanded treatment is parathyroidectomy which should preferably be performed during the second trimester of pregnancy; the efficacity of medical treatment is poor and transient.