The high arsenic concentrations reported in literature for Laccaria amethystina were amply confirmed. In addition, it was demonstrated that Laccaria fraterna also accumulates the element, whereas in other species of Laccaria the phenomenon was far less outspoken. Few other basidiomycetes proved to have an affinity for the toxic element. The arsenic concentrations in the principal edible mushrooms of commerce were found to be very low, i.e. on the average 0.5 mg/kg on dry matter. Among the ascomycetes Sarcosphaera coronaria was recognized as an accumulating species. The arsenic content of four collections ranged from 360-2130 mg/kg with an average of 872 mg/kg on dry matter.