The aim of the study was an assessment of the antioxidant, antifungal and cytotoxic potentials of L. betulinus and T. hirsuta mycelia extracts and the effect of selenium on these activities. Extracts of L. betulinus were twice as efficient in DPPH• scavenging as those of T. hirsuta. The phenol content in Se-enriched L. betulinus extracts was higher than in non-enriched extracts, in contrast to the effect of Se-enrichment on T. hirsuta extracts, and a direct correlation between the amount and DPPH• scavenging effect was observed. Ethanol extracts exhibited fungistatic but not fungicidal activity against a range of micromycetes, and mycelium enrichment with selenium inhibited this effect. Although the extracts showed low cytotoxic activity against HeLa and LS174 cells, T. hirsuta extracts, especially those enriched with selenium, had better potential. L. betulinus extracts showed better antioxidant and antifungal activity than T. hirsuta extracts which were more active cytotoxic agents. The presence of selenium stimulated antioxidant and cytotoxic, and inhibited antifungal activity in L. betulinus, while in T. hirsuta its effect was slight.