Abstract In an attempt to enrich the fruiting bodies with Lithium (Li), this study cultivated mushrooms using growing sets that were fortified with Li 2 O at 1.0, 5.0, 10, 50, 100 and 500 mg·kg −1 dw. Compost fortification up to 100 mg·kg −1 dw induced a dose-dependent increase in Li accumulation with resulting median mushroom concentrations of 2.0, 8.6, 16, 29 and 38 mg·kg −1 dw, respectively, relative to the unfortified control at 0.087 mg·kg −1 dw. The dose dependency appears to level off as Li 2 O addition approaches 100 mg·kg −1 , suggesting that there is a limit to the ability of the species to accumulate/tolerate Li. Mushrooms did not grow at the 500 mg·kg −1 dw fortification level. At the highest viable level of fortification (100 mg·kg −1 dw), the fruiting bodies were around 440-fold richer in Li content than the control mushrooms. Additionally, the fortification at all levels up to 100 mg·kg −1 dw showed very low, if any, effect on the co-accumulation of the other, studied trace mineral constituents, with concentrations occurring at the lower range of those reported for commercial A. bisporus mushrooms.