Here, we compare the immunohistochemical profiles in a series of 53 cases of normal tissue adjacent to prostatic adenocarcinoma (NAC), 17 cases of benign prostatic hyperplasia (BPH), 35 cases of prostatic intraepithelial neoplasia (PIN), 107 cases of PCa, and 55 cases of metastatic prostatic adenocarcinoma (Mets) in order to obtain a more complete understanding of the immunostaining profile of claudin-3 in primary and metastatic prostate cancer and to further examine its potential as a biomarker for prostate cancer and/or prostate cancer metastasis. This evidence concerns the gene CLDN3 and prostate cancer.