The goal of the study was to analyze the expression of p27(Kip 1) cyclin-dependent kinase inhibitor protein (CDKI) in different cells of benign, malignant and hormonally treated prostate cancer tissue and assess their possible association with different clinical parameters. Expression of p27(Kip 1) CDKI was evaluated and compared in: 32 BPH, 20 prostate cancer (PCa) and 6 hormonally treated prostate cancer (HTPCa) tissues. Intensity of the expression was compared between the groups and association was soughed with the cancer clinical parameters. Total expression of p27(Kip 1) was significantly higher in BPH as compared with PCa (p=0.0002) and HTPCa (p=0.0324). The difference between PCa and HTPCa was not significant. p27(Kip 1) was higher expressed by epithelial, ductal and vascular prostatic cells of BPH as compared with PCa (p=0.0001, 0.0101 and 0.0224, respectively). The stromal expression of the marker was not different between the groups. Epithelial marker expression was significantly increased in HTPCa as compared with PCa (p=0.0460). In the PCa group, the intensity of the protein expression was negatively associated with the tumor stage, Gleason scores 1, 2, and the Gleason sum (p=0.0453, 0.0202, 0.0074 and 0.0098, respectively). This difference was found in epithelial, vascular and ductal prostatic cells. Down-regulation of p27(Kip 1) CDKI in PCa is detected in epithelial, vascular and ductal, but not the stromal cells. The intensity of the expression in these cells is associated with tumor stage and grades. The hormonotherapy is causing up-regulation of p27(Kip 1) expression in prostate adenocarcinoma cells.