Introduction and objectives. Many epidemiological and experimental studies report a strong role of chemical carcinogens in the etiology of bladder cancer. However, the involvement of heavy metals in tumourigenesis of urothelial carcinoma of the bladder has been poorly investigated. Therefore, the aim of this study was to examine the relationship between chromium (Cr) and bladder cancer. Materials and methods. Chromium concentration in two 36-sample series of bladder cancer tissue and sera from patients with this neoplasm were matched with those of a control group. The amount of trace elements in every tissue sample was determined using atomic absorption spectrometry. This was correlated with tumour stage. Results. While the median chromium concentration levels reached statistically higher values in the bladder cancer tissue, compared with the non-cancer tissue (99.632ng/g and 33.144ng/g, respectively; p<0.001), the median Cr levels in the sera of the patients with this carcinoma showed no statistical difference when compared to those of the control group (0.511μg/l and 0.710μg/l, respectively; p=0.408). The median levels of Cr in the bladder tissue, depending on the stage of the tumour, compared with the tissue without the neoplasm, observed the same relationship for both non-muscle invasive and muscle-invasive tumours (p<0.001 and p<0.01, respectively). Conclusions. This study shows that patients with urothelial carcinoma of the bladder had higher tissue Cr levels than people without tumour, while no difference was found in the Cr serum levels between the two groups of patients under investigation.