Breast cancer is the most common cancer of women worldwide. It is a heterogeneous disease. The incidence rate of this disease increased in the last years in Iraq. The current study was conducted to study the immunohistochemical and molecular parameters for the breast tumors by using tissue microarray (TMA) technique on Iraqi patients with breast carcinoma. Tissue microarrays (TMAs) are a new high-throughput tool for the study of protein expression patterns in tissues and are increasingly used to evaluate the diagnostic and prognostic importance of biomarkers. Tissue microarray is a recent innovation in the field of pathology. A microarray contains many small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allows high throughput analysis of multiple specimens at the same time. Tissue microarrays are paraffin blocks produced by extracting cylindrical tissue cores from different paraffin donor blocks and re-embedding these into a single recipient (microarray) block at defined array coordinates. Using this technique, up to 1000 or more tissue samples can be arrayed into a single paraffin block. It can permit simultaneous analysis of molecular targets at the DNA, mRNA, and protein levels under identical, standardized conditions on a single glass slide, and also provide maximal preservation and use of limited and irreplaceable archival tissue samples. This versatile technique, in which data analysis is automated facilitates retrospective and prospective human tissue studies. It is a practical and effective tool for high-throughput molecular analysis of tissues that is helping to identify new diagnostic and prognostic markers and targets in human cancers, and has a range of potential applications in basic research, rognostic oncology and drug discovery.Histopathological data for the patients were obtained. Formalin-fixed, paraffin-embedded (FFPE) samples were used in this study. Two TMAs recipient blocks were designed and constructed for samples. Sixty Iraqi breast cancer cases used as the TMA block breast cancer. For TMAs construction, each donor sample were represented in duplicate, cores were transferred from each donor patient sample to the recipient block. Hematoxylin and Eosin (H and E) stained then immunohistochemically (IHC) studied for murine double minute (MDM2), cytokeratin (CK5/6, CK8/18) for the TMAs. The mean age of the Iraqi breast cancer patients in this study (50.32±11.85) years old; ranging from 23-80 years old. Histological Grade I, II and III were detected in 13.3%, 70.0% and 16.7% respectively. 81.4% of cases had positive lymph node metastasis MDM2 positive expression was found in 33 (62.3%) out of 60 cases of the Iraqi breast cancer cases. CK5/6 expression was observed in 5(8.9%) and CK8/18 expression was observed in 39 (69.6%) out of 60 samples of the Iraqi breast cancer. The study revealed that there was a significant relationship between the MDM2 and CK8/18 expression and Lymph node status and there was significant relationship between Ki67 expression with the histological grade (P value<0.05). The results indicated that the Iraqi breast cancer cases used in this study were phenotypicaly more aggressive. We utilized TMA sections for the validation of the MDM2, CK5/6 and CK8/18. In conclusion, TMA was successfully used as a rapid, economic and effective method for IHC studies.