Objective:To evaluate the overexpression of Her-2/neu in patients with breast cancer in Mosul (both invasive and intraductal) against other prognostic parameters of mammary carcinomas, such as histological type, grade, tumor size, patient age and number of lymph nodes involved. Methods: This is a retrospective study conducted in the Pathology laboratory of Al-Jamhoori Teaching Hospital and at private laboratories. A total of 36 breast cancer cases and 4 benign cases were diagnosed and collected in a period spanning from April 2006 to April 2007. We used Immunohistochemistry to evaluate the overexpression of Her-2/neu against the age, tumor size, type and grade and the axillary lymph node status. Results: The mean age of all cases was 47.5 years ranging from 28 to 72 years. Regarding the age, Her-2 positivity was shown in 2 peaks (4 th and 7 th decades), while Her-2 negativity was found in older age group (p=0.004). Overall Her-2 overexpression was in 37% of the cases; it was overexpressed in 34.5% of invasive ductal carcinoma, in 100% of medullary carcinoma and in 100% of ductal carcinoma in situ. Whereas no expression (0.0%) was seen in 3 cases of invasive lobular carcinoma and one case of colloid carcinoma. Her-2 positivity was associated with large size (T2 and T3) rather than small size tumors (p=0.015). There was a correlation between Her-2 positivity and high grade tumor [G3 in 69.2% of the positive cases (p=0.045)]. Her-2 positivity was associated with axillary lymph node metastasis in 84.6% of cases, but not reaching a statistical significance. The benign lesions included in this study (two fibroadenoma, one fibrocystic disease and one duct ectasia) all showed negativity for Her-2 stain. Conclusion: Her-2 overexpression was found in 37% of breast cancer in Mosul. Regarding age incidence Her-2 overexpression was noted at 2 peaks 3 rd and 6 th decades. Large size and high grade breast carcinomas were associated with high percentage of Her-2 positivity, and the majority of Her-2 positive cases had axillary lymph node metastases.