Background: Hashimoto's thyroiditis has been found to coexist with differentiated thyroid cancer in surgical specimens, but an association between the two conditions has been discounted by the medical literature. So, we performed this research to determine any potential relationship between Hashimoto's thyroiditis and the risk of developing differentiated thyroid cancer in clinical status. we assessed the related clinical factors linking these conditions, especially serum thyroid-stimulating hormone concentration, family history of thyroid disease, gender& young age group. Aim of study: to determine that hashimoto’s thyroiditis increases risk for differentiated thyroid carcinoma. Patients and method: This study is a Cross-sectional study carried out in surgical ward of Baghdad teaching hospital, where 82 patients followed up for one year from 1/10/2017 to 1/10/2018. Clinical history and examination with thyroid function tests, ultrasound and FNAC done for them pre operatively, post-operatively all thyroid specimen sent for histopathological study. Results: Differentiated thyroid cancer with Hashimoto's thyroiditis patients: (84.6%) had papillary thyroid cancer with Mean age of patients is 37.3±3.3 and Female gender represents 92.3% of differentiated thyroid cancer with Hashimoto's thyroiditis patients. About 53.8%of differentiated thyroid cancer with Hashimoto's thyroiditis patients had high thyroid-stimulating hormone at presentation. About 61.5% of differentiated thyroid cancer with Hashimoto's thyroiditis patients had positive family history of thyroid disease. Most our patients had multinodular goiter 80.5%, only 19.5% had single nodule, in Differentiated thyroid cancer with Hashimoto's thyroiditis patients (papillary thyroid cancer: 81.8% multinodular goiter and18.2% Single nodule, while all Follicular Thyroid Cancer patients had multinodular goiter).Fine needle aspiration biopsy in diagnosis of Hashimoto's thyroiditis pre-operation had Sensitivity 61% & specificity98%.