Objective: We aimed to evaluate the frequency and clinicopathological features of papillary thyroid carcinomas synchronized with parathyroid adenoma and to compare the “parathyroid adenoma with papillary thyroid carcinoma” and “parathyroid adenoma without papillary thyroid carcinoma” groups. Methods: The study included 287 parathyroid adenoma cases that had concomitant thyroid surgery. Age, gender, parathyroid adenoma characteristics, diagnosis for thyroid materials, and clinicopatho logical prognostic parameters for papillary thyroid carcinomas were recorded from the pathology reports. Results: Synchronous parathyroid adenoma and thyroid malignancy rate was 27.2%, and papillary thyroid carcinomas were 88.5% of the malignancies. Papillary thyroid carcinomas were mostly seen in female patients and in right thyroid lobe, the multifocality rate was 18.8%, the follicular variant being the most common, the majority were papillary microcarcinomas and pT1 tumors, extrathyroi dal extension rate was 13%. “Parathyroid adenoma with papillary thyroid carcinoma” and “parathyroid adenoma without papillary thyroid carcinoma” groups were statistically similar in the patient and parathyroid adenoma characteristics. Intrathyroidal parathyroid adenomas and the right parathyroid gland involvement were more common in “parathyroid adenoma with papillary thyroid carcinoma” group, while multiple parathyroid adenomas and left parathyroid gland involvement were more common in “parathyroid adenoma without papillary thyroid carcinoma” group. Inferior parathyroid gland involvement was more common than the superior, and the mean parathyroid adenoma size was similar for both groups. Conclusion: Synchronous parathyroid adenoma and papillary thyroid carcinoma cases are not uncommon, and detection of papillary thyroid carcinoma may change the surgical procedure. Therefore, all parathyroid adenoma cases should be thoroughly investigated for concomitant thyroid pathologies before surgery. Keywords: Papillary thyroid ca