Background: The  association of  Epstein Barr virus (EBV) with breast carcinomas (BCs) is still in controversy. The aim of this study was to clarify the association of EBV & BC in Egyptian females and  to assess  its role as potential contributor to the development and behavioral alteration of BC.  Subjects & methods: EBV-DNA was detected using PCR on breast tissue from 40 female patients with primary invasive BC; ductal (n=32) and lobular (n=8) and  20 age matched females undergoing  reduction mammoplasties as control.  Results: EBV-DNA was detected in 8/40 (20%) BC specimens. On the other hand all control specimens were negative As regards prognostic factors, no association was observed between EBV-DNA and patients' age, menopausal status and steroid receptor expression. However, significant associations were detected between the presence of EBV-DNA and other poor prognostic factors. All of the EBV-DNA positive BC were significantly associated with positive nodal status, where 7/8 cases showed more than three tumor-positive LN involvement.   In spite of the small number of invasive lobular carcinoma included in this study there was a significant correlation between this histological type of poor prognosis and EBV-DNA detection rate where 4/8 (50%) of them were positive for EBV-DNA compared to 4/32 (12.5%) detection rate in invasive ductal carcinoma. A significant correlation was found between EBV-DNA detection rate in BC and high tumor grade of invasive ductal carcinoma; (100%, 1/1) association with grade III versus (9.67%; 3/ 31) with grade II. Conclusions: our results demonstrated the presence of the EBV genome in a considerable subset of BC in Egyptian patients. The virus was more frequently associated with bad prognostic factors. This indicates that EBV may play a role in the development and behavioral alteration of some aggressive BC.