Prostate cancer (PC) is the most common malignant disease in men. Prognosis of patients with metastatic PC is generally unfavourable; however there are significant differences in survival at this stage of the disease. The definition of prognosis is essential for the selection of therapy, respecting an individual risk. In recent years, the association between circulating tumor cells (CTC) detection and response to PC treatment has been widely investigated. Detection of CTC is based on a metastatic process theory and uses well-known tumor-specific antigens on the cell surface. Individual methods assess CTC with different sensitivity and are not yet efficient at the localised PC stage. Only the method of immunomagnetic separation and semi-automatic visualisation (CellSearchTM) has been validated and approved for the use in the PC management. Assessment of the CTC count directly correlates with the prognosis of patients with castration-resistant PC. Change in the CTC count during the therapy also considerably improves risk estimation and represents a marker of overall survival. New methods of CTC cultivation and gene profiling may contribute to individualisation of the treatment similarly to breast cancer. The authors present a review article about theory, methods of detection and clinical use of CTC in castration-resistant PC.