The aim of this study was to determine the degree of mercury tissue contamination of bream, so often consumed by man. Taking into account a significant reduction in Polish industry production, reduced use of chemicals in agriculture and the installation of several waste recycling water plants in the Vistula River basin, it was interesting to determine possible mercury contamination changes in water and then in fish. The study was performed in the middle course of the Vistula River, where 30 pieces of bream were caught (15 in each examined year) weighing 0.75-1.0 kg. Mercury was determined by the ASA method using the automatic analyser TMA-254. In 1990 the range of Hg concentration in muscles of bream was from 0.157 to 0.298 and in 1993 was about two times lower and varied from 0.068 to 0.175 mg.kg(-1). It seems to us, that it was caused by a decrease of mercury water contamination. The observed level of bream muscle contamination does not exceed the acceptable norms for mercury content established by FAO/WHO as well as the Polish Ministry of Health.