SUMMARY This work aimed to study the expression of the oncofetal protein IMP3 on different thyroid lesions and to detect its role in differentiating benign from malignant thyroid lesions. We performed an immunohistochemical study using the Avidin-Biotin peroxidase technique on formalin-fixed paraffin-embedded tissue sections, and correlated the results of staining with the patient clinical and pathological data such as age, sex, grade, size, lymphatic/vascular invasion, capsular invasion, nodal metastasis and TNM stage. The current retrospective study was carried upon 63 thyroid cases collected from Department of Pathology and Early Cancer Detection Unit; Banha faculty of medicine from 2013 to 2017; composed of 6 cases of apparently normal thyroid tissue, 7 cases of hashimoto thyroiditis, 10 cases of hyperplastic nodules, 15 cases of follicular adenoma, 13 cases of papillary thyroid carcinoma, 6 cases of follicular variant of papillary thyroid carcinoma and 6 cases of follicular thyroid carcinoma. Fifty-two (91.2%) cases were 0.05). We found increased expression for IMP3 in tumors with higher grade (grade II and III) (69.2% and 66.7 5 positivity, respectively) and with tumors with larger size (100% positivity in T3 tumors) which was statistically significant (P0.05)