Introduction: The nuclear factor ${kappa}B$ (NF-${kappa}B$) is a super family of transcription factors which plays important roles in development and progression of cancer. The present investigation concerns NF-${kappa}B$ /p65 activity in human breast cancers with overexpression of ER, PR, HER-2/neu, as well as the significance of p65 expression with regard to menopausal status, stage, grade, tumor size, nodal status, and NPI of invasive ductal carcinomas in Eastern India. Materials and Methods: In this hospital based study 57 breast cancer patients attending a Breast Clinic of a reputed institute of Eastern India were assessed for p65 protein expression in breast tumor tissue samples by Western blotting. ER, PR and HER-2/neu expression was determined by immunohistochemistry. Results: NF-${kappa}B$/p65 was significantly associated with advanced stage, large tumor size (${geq}5$ cm), high grade, negative ER, negative PR, and positive HER-2/neu. High NF-${kappa}B$/p65 expression was more frequent in patients with a high NPI ($NPI{geq}5.4$, 84.6%) compared with low NPI (<5.4, 44.4%) and this association was statistically significant (p = 0.002). Conclusion: NF-${kappa}B$/p65 overexpression was associated with advanced stage, large tumor size, high grade, and high NPI which are poor prognostic factors linked to enhanced aggressiveness of the disease. NF-${kappa}B$/p65 expression implies aggressive biological behavior of breast cancer and this study validates significant association of NF-${kappa}B$ /p65 overexpression with negative estrogen and progesterone receptor status and overexpression of HER-2/neu oncoprotein. In our good clinical practice, patients with NF-${kappa}B$ positive tumors need to be treated aggressively.