During assessment of the progression of several types of carcinomas, such as cancer of the breast, lungs, prostate or urinary bladder world-wide the presence of circulating cells (micrometastases) in the circulation is followed up. These methods are gradually introduced also in Slovakia. First we tried in the Institute of Medical Biology and Genetics Medical Faculty Comenius University in collaboration with the Urological Clinic of Dérers the Faculty Hospital with policlinic to apply this method in carcinoma of the prostate (CaP). We detected the presence of epithelial prostate cells in the peripheral blood stream of patients with advanced prostate cancer where before secondaries were not detected.