Objective: Hashimoto’s thyroiditis is the most common autoimmune thyroid disease. Papillary thyroid cancer is the most common thyroid cancer. Whether Hashimoto’s thyroiditis is a predisposing factor for papillary thyroid cancer remains unclear. In this study, the frequency of papillary thyroid cancer was investigated in patients with Hashimoto’s thyroiditis who underwent total thyroidectomy. -/- Methods: In this study, 534 patients were screened retrospectively. Preoperative thyroid function tests, anti-thyroid antibodies, ultrasonography findings, fine-needle aspiration biopsies, and thyroidectomy pathology results were (...) examined. According to the pathology, 139 patients had Hashimoto’s thyroiditis. Patients with Hashimoto’s thyroiditis (group 1) and non-Hashimoto’s thyroiditis (group 2) were compared. -/- Results: Papillary thyroid cancer was found in 70 patients (50.4%) in group 1 and 156 patients (39.5%) in group 2 (P=.026). The odds ratio was 1.59 (95% CI; 1.07-2.34). There was no difference for sex, age, tumor size, microcarcinoma–macrocarcinoma distribution, subtype, number of tumor focus, lymph node metastasis, vessel invasion, and extrathyroidal spread. -/- Conclusion: We found more papillary thyroid cancer and less capsular invasion in patients with Hashimoto’s thyroiditis, but we did not find any differences between groups in terms of age, gender, tumor size, vascular invasion, and metastasis. According to these findings, Hashimoto’s thyroiditis may be a risk factor for papillary thyroid cancer. (shrink)