BACKGROUND. Prostate cancer (PCa) is the second most common tumor type related to mortality in males in the developed countries. Studies have demonstrated that therapeutic tools mostly ineffective to give positive outcome especially for PCa. Cancer stem cells are composed of a small cell population, which are supposed to have roles in tumorigenesis, metastasis, and tumor recurrence after chemo-radiotherapy. The aim of this research is to investigate expressions of stem cell markers in recurrent PCa and non-recurrent PCa tumors as well as in adjacent normal prostate tissues.