A good biomarker is defined as any test (molecular, morphometric, etc.) that adds independent information to standard prognostic indicators (e.g., pathologic evaluation or clinical stage), that can be reliably reproduced in the laboratory setting, and that aids in choosing treatment options (1). The primary objective of this study was to determine if the proliferation marker Ki-67, a nuclear antigen and molecular marker known to be associated with the progression of cancer, had significantly different levels of expression in normal prostate tissue, high-grade prostatic intraepithelial neoplasia (HGPIN), and prostate adenocarcinoma (PCA) (2). The secondary objective was to determine the degree to which the Ki-67 biomarker expression in sextant needle biopsy specimens (i.e., sections that represent the standard sextant regions [right-apex, right-mid, right-base, left-apex, left-mid, and left-base]) accurately represents expression in wholemount radical prostatectomy (RP) specimens. If Ki-67 expression in corresponding tissue is the same in presurgical biopsy and RP specimens, then it should be possible to measure what happens to this biomarker in response to interventions in the neoadjuvant setting (i.e., treatments before surgery) and in chemoprevention trials intended for healthy men.