Mercury was quantified in the fruiting bodies of 15 species of higher mushrooms and underlying soil substrate collected from the Tarnobrzeska Plain in south-eastern part of Poland in 1995. In total, 405 samples each of caps, stalks or whole fruiting bodies and 221 samples of soil (0 10cm layer) were examined. The area under investigation can be considered generally as unpolluted with mercury since the mean concentrations in underlying soil substrate of 14 mushroom species were between 21 +/- 9 and 58 +/- 31 ng/g dry wt. (total range between 4.5-240). Somewhat elevated concentrations, of 630 +/- 80 ng/g dry wt., were noted for underlying soil substrate of Livid Entoloma (Entoloma sinuatum). Among the mushroom species examined, King Bolete (Boletus edulis), Livid Entoloma, and Red-capped Scaber Stalk (Leccinum rufum) contained the greatest mercury concentrations both in the caps (between 1,800 +/- 600 and 3,500 +/- 1,100 ng/g dry wt.) and stalks (between 900 +/- 400 and 2,300 +/- 1,000 ng/g dry wt.). Because of the relatively great bioconcentration factors (BCF) of mercury, which averaged between 73 +/- 44 and 220 +/- 270 in the caps, and between 37 +/- 28 and 170 +/- 240 in the stalks, King Bolete, Bay Bolete (Xerocomus badius) and Red-capped Scaber Stalk can be considered as good mercury accumulators. Nevertheless, apart from the Common Earth Ball (Scleroderma citrinum), that can be considered as an excluder of mercury due to the BCF value of less than 1, other species examined were characterised by BCFs greater than 1. The caps were usually characterised with greater mercury content than the stalks (Hg(Cap)/Hg(stalk) quotients > 1) and the reverse was noted only for Bay Bolete. Due to a statistically significant relationship between mercury content of the caps/stalks and underlying soil substrate (p<0.001) in Filamentous Pax (Paxilus filamentosus), and in the stalks of Red-capped Scaber (p < 0.05) and Brick Tops (Hypholoma sublateritium) (caps; p < 0.05), these species can be suggested to exhibit bioindication potential for soil mercury contamination.