OBJECTIVE: Prostatic diseases are a major cause of morbidity and mortality. The need is to detect the disease early in its natural history and manage it aggressively. Prostate-specific antigen (PSA) is not very sensitive, thus other indices are being employed. Argyrophillic nucleolar organizer region (AgNOR) count is the proliferative index marker used in our study. Our main objective was to evaluate the role of AgNOR in prostatic lesions and to find a correlation between serum PSA and AgNOR counts. PATIENTS AND METHODS: We evaluated 60 patients of prostate diseases over a year. The patients were classified as benign prostatic hyperplasia (BPH), prostatitis, or prostatic adenocarcinoma (Ca). Patients with suspicious areas or foci of prostatic intraepithelial neoplasia (PIN) on histology were subjected to a slide review. All slides were H&E and AgNOR stained. RESULTS: The difference between the mean AgNOR counts of BPH and prostatitis was significant, as between BPH and PIN (p < 0.001). The difference between low- and high-grade PIN was also significant.Ca prostate showed a significant increase in AgNOR counts from benign diseases; and also between localized and metastatic carcinoma (p < 0.001). On finding a correlation between serum PSA values and AgNOR counts, they were significant for benign and carcinoma cases (p < 0.001), though not for PIN. CONCLUSIONS: Our study depicts the usefulness of AgNOR counts in the diagnosis of various prostatic diseases including the pre malignant PIN. The relation between serum PSA and AgNOR was highly significant for BPH and Ca prostate. Hence, AgNOR is an efficient adjunct to our diagnostic armamentarium leading to improved prognostication and management.