Prostate cancer is the second most common cause of male cancer deaths. Recently studies have revealed the role of estrogen signaling pathways in the carcinogenesis of prostate. Estrogen regulates the growth of prostate through two receptors, ER-α and β, of which ER-β is proposed to be antiproliferative. It is noted that there is wide variation in results of various studies regarding the level of expression of ER β in benign and malignant prostatic lesions. There is need of additional research to standardize distribution of this receptor in human prostatic tissue. Aim: To evaluate the immunoexpression of ER-β and Ki67 in benign and malignant prostatic lesions. Methods: A hospital-based retroprospective study was conducted. Paraffin blocks of Benign Hyperplasia of Prostate(BPH) and carcinoma prostate were retrieved from Histopathology Section in the Department of Pathology. IHC evaluation of ER-β and ki67 was performed in these cases and the expression of these markers was compared between the two groups. Results: 40 cases of BPH and 40 cases of Adenocarcinoma of prostate were included in the study. Comparison of the Immunohistochemistry marker ER-β and ki67 was done between the two study groups. Ki67 showed high sensitivity of 100% and specificity of 75% and ER-β showed sensitivity and specificity of 95% and 45% respectively and was statistically significant. Conclusion: There was reduced ER-β expression in adenocarcinoma prostate when compared to Benign Hyperplasia. In contrast , Ki67 expression showed higher expression in carcinoma prostate.