Clinically relevant findings: Hepsin expression was determined to be 100% among prostate carcinoma cases, 11.9% (5/42) in benign prostatic hyperplasia, 57.14% (4/7) in benign prostatic hyperplasia with prostatic intraepithelial neoplasia (PIN), and 0% in benign prostatic hyperplasia with prostatitis. Hepsin staining intensity significantly correlated with high-grade disease when compared to low-grade disease.