Background: Primary hyperparathyroidism in pregnant women is a rare antenatal complication. Maternal symptoms include nephrolithiasis, bone disease, pancreatitis, hyperemesis, muscle weakness, mental status changes, and hypercalcemic crisis. Fetal complications comprise intrauterine growth retardation, low birth weight, preterm delivery, intrauterine fetal death, postpartum neonatal titanic crisis, and permanent hypoparathyroidism. Case: A 23-year-old gravida was referred to our clinic with severe hyperemesis and weight loss at 32 gestational weeks. She was diagnosed with primary hyperparathyroidism because of parathyroid adenoma and treated with surgery where a synchronous thyroid papillary carcinoma was detected. After right parathyroidectomy and right subtotal lobectomy of the thyroid, the patient was stable and laboratory and clinical findings normalized. The fetus' state was monitored via reassuring non-stress cardiotocography and repeated sonographic exams until birth. Delivery was induced at 35 weeks of gestation because of preeclampsia. Conclusion: Parathyroid adenoma in pregnancy is a rare maternal condition with potential impact on the advancing pregnancy. Generally, a surgical approach is recommended with thorough inspection of the thyroid gland so that any irregular structure might be removed during the same surgical intervention for diagnostic reasons. In this reported case, a coexistent papillary carcinoma of the thyroid was detected accidentally and removed successfully.