The association between parathyroid and thyroid diseases is not uncommon; however, the concurrent presence of parathyroid adenoma and thyroid cancer is rare. Awareness of this situation will enable clinicians to consider possible parathyroid pathology in patients with papillary thyroid cancer. The presence of parathyroid adenoma leading to primary hyperparathyroidism and the coexistence of thyroid papillary cancer is rare. We report a case of a 55-year-old female with papillary cancer admitted for surgery. Preoperative laboratory findings revealed normal calcium level and normal intact parathyroid hormone (PTH) level. Thyroidectomy and excision of abnormal enlarged double parathyroid glands were performed. Histological examination revealed parathyroid adenoma. Serum calcium was within the normal range after surgery. We recommend a preoperative check of calcium in patients with thyroid cancer.