In the present thesis called "The modern analytical methods for detection of aminoacids asociated with malignant prostate tumours" sarcosine has been studied as a potential tumor marker which has significance for the diagnosis of aggressive forms of prostate cancer. The effect of addition of sarcosine prostate line PC3 has been also studied as well. Next studied area were the the interactions with amino acid sarcosine, sodium chloride, uric acid and uracil. We have primarily focused also on the development of methods for the detection of sarcosine in urine samples of patients with Cap and prostate cells.