Abstract Background: Hashimoto?s thyroiditis is a common lifelong autoimmune disease of the thyroid gland. Case Presentation: A 63-year-old woman was clinically diagnosed as non toxic goiter. Thyroidectomy was done and specimen was sent for histopathological examination. A brownish and soft mass was received with size 6x5x4cm. Microscopic examination showed that proliferation of lymphoid follicles with germinal center of lymphoplasmacytic cells between acini. Some of acini were destroyed and atrophic, while some of them formed microfollicular structures. Acini were lined by simple cuboid epithelium with round oval nuclei, fine chromatin, and eosinophilic cytoplasm. Most of acini contained colloid inside lumen. Lying in between acini were found oncocytic cells with round nuclei, some with prominent nucleoli, fine chromatin, abundant and granular cytoplasm. Stroma consisted of fibrous connective tissue. Conclusion: Histopathological examination yielded the diagnosis of Hashimoto?s thyroiditis.