Background. Primary hyperparathyroidism is rare in pregnancy. An association between primary hyperparathyroidism and preeclampsia has been reported in few cases worldwide. Case. A 28-year-old woman (gravida 2, para 0, and abortus 1) in her 27th week of gestation was hospitalized due to a high reading of blood pressure (194/115 mmHg) that was not accompanied by any symptoms or signs of preeclampsia. Incidentally, she was found to have a high adjusted calcium and serum parathyroid hormone (PTH) level during admission. Ultrasonographic examination of the neck revealed the presence of parathyroid adenoma. She was scheduled for surgical excision after receiving an intravenous hydration. Fetal ultrasonography revealed a growth restricted fetus with normal biophysical profile. On the sixth day of hospitalization, the patient complained of headache and epigastric pain, with elevated BP and proteinuria. The fetal nonstress test was "nonreassuring." Subsequently, she had an emergency cesarean delivery and surgical removal of the adenoma. The mother and her newborn were then transferred to intensive care, where their clinical course was unremarkable. The mother was discharged after 3 days, while the neonate stayed for close observation for 60 days. Conclusion. Early recognition of primary hyperparathyroidism among women with preeclampsia is important to prevent maternal and fetal morbidity and mortality.