The diploma thesis deals with the accumulation of mercury in fungi, soil and litterfall. Mercury and heavy metals are generally a common part of the environment, but some organisms tend to accumulate mercury and other heavy metals. If such organisms enter the food chain in large quantities, poisoning of an individual or a group of the population may occur. In our case, the organism is a fungus. We examined the mercury content in 20 samples of mushrooms collected from 6 different localities in the Krupinská planina. Along with the mushrooms, we also took soil and litter samples to find the relationships between the mercury content in those three components of the environment and to identify anomalies in the results. The results were analyzed by a single-purpose atomic spectrophotometer AMA 254 and compared with the legislative limit of the Slovak Republic. We measured the increased concentration of mercury in 5 samples of fungi, while all samples of soil and litterfall were under the limit. The highest measured value in the fungus reached 6.103 ± 0.898 mg.kg-1 and the average measured value was 0.730 mg.kg-1.