The purpose of the studies was to measure the content of mercury in 35 pieces of kidneys of hares (Lepus europaeus) from five regions of Poland and in 16 pieces of kidneys and livers of hares coming from two regions of the Czech Socialist Republic. The analyses were done using the apparatus TMA 254 and the method of atomic absorption spectrophotometry in separated cortex and medulla of the kidneys. The results were compared taking into account the regions, origin of hares, influence of industry, intensity of agricultural production, sex and age. There was a difference in the mercury content in the cortex and medulla of the kidneys with as much as twofold concentration found in the cortex. At the same time, higher content was registered in older animals and in males. As to the place of origin the highest concentrations were found in the regions characterized by fall of emissions, industrial centres of Lodz and Zgierze, in the regions with intensive farming, the lowest concentrations were observed in the territories with minimum of industry and prevalence of private farming. In hares hunted in two regions of the Czech Socialist Republic, higher level of mecury was confirmed in the cortex than in the medulla. There were higher values in the liver and in the kidneys of hares from the vicinity of Stara Boleslav than from that of Kolin. This study presents an evidence of the fact that the analysis of the tissue of hares is convenient for gaining information about the level of mercury contaminating the environment. However, in the regions under study the content of this heavy metal does not surpass significantly the highest tolerable concentrations. It can also be concluded that mercury is present more as a result of an industrial activity than as a result of intensity of agricultural production.