The aim of the investigation was establishing the degree of mercury contamination of various capped mushrooms collected in various regions of Poland varying as to the degree of environmental contamination resulting from the industrialisation of that region. The establishing of the species and habitat differences would allow the determination of the bioindicative value of mushrooms in case of contamination the environment with mercury. The investigating of mercury level in mushrooms may constitute an element of bioindication of environmental contamination with that heavy metal. Mushrooms selectively accumulating mercury obtained from contaminated regions may constitute an important source of that element for human beings.