Background & Objective: Despite, lymphocytic infiltrate (LI) is reported in benign prostatic hyperplasia (BPH) and prostate carcinoma (PC), its role in BPH progression to PC is still an issue of debate. The aim of this study is to investigate this role through correlation of LI of nuclear factor kappa B (NFκB), and cyclinD1 hoping to bargain a diagnostic, therapeutic and/or preventive target in PC management. Material and methods: we studied 100 BPH cases and fifty percent of them had PC on top. Archived paraffin blocks were microtomed at 4-5 µm and rolled in hematoxylin and eosin stain to revise diagnosis and grading, in addition to immunohistochemical analysis using antibodies against CD3, CD20, NFκB, and cyclin D1 and then correlate these results with Clinicopathological variables. The results: we found LI in both BPH and PC cases with a predominance of T-lymphocytes over B-lymphocytes. There was a statistically significant correlation of LI to NFκB (p value˂0. 001), and cyclin D1 (p value˂0.001), and a statistically significant correlation of NFκB to cycling D1was detected (p value˂0. 001). CyclinD1 is exclusively expressed in the malignant prostatic epithelium. Conclusion: the tense LI detected in prostate hyperplasia and carcinoma may activate NFκB and that in turn may induce epithelial cell proliferation through cyclinD1 overexpression and neoplastic transformation. Cyclin D1 can be used to differentiate between BPH and PC.