Introduction. The participation of cytokines in the development of inflammation is well documented, while recently attention is paid to their role in the pathogenesis of the cancer process. Cytokines show very different, and also diverse action on the cancer progression. The aim of the study was to estimation whether the determination of concentration two interleukins: IL-8 and IL-18 in the urine may be helpful in the diagnosis of bladder cancer.<br>Material and Methods. The material for examinations was morning urine and serum of patients diagnosed with bladder cancer, verified histopathologically with staging according to TNM (Tumor Nodules Metastases) and grading according to WHO (World Health Organization) classification. Interleukins concentration was determined in the urine by immunoassay method ELISA (Diaclone, R & D Systems).<br>Results. In patients with bladder cancer, significantly higher mean concentration of both interleukins and total protein in urine were found. The concentration of C-reactive protein in serum was not significantly higher than the value in healthy people. A significant positive correlation was found between the concentration of IL-8 in the urine and the staging (T) and grading (G) of the tumor. There were no such dependences for IL-18.<br>Conclusions. Changes in IL-8 concentrations in the urine may be helpful in diagnosing patients with bladder cancer. However, the studies conducted due to the small number of patients may not be able to be referred to the general population, and therefore further estimation of interleukin 8 concentration changes is require in order to confirm its diagnostic potential.