[Biodiversity of lichen-forming fungi on Fekete Hill (Szentbékkálla, Hungary)]. Biodiversity of lichen-forming fungi was studied in July 2009 in the framework of the 5th Hungarian Biodiversity Days. Lichens from bark of deciduous and coniferous trees, acidic rocks and soil were sampled in the investigation area of 2 km2. Altogether 105 species (with 260 occurrence records) were found. Comparing this number to the total number of species of all investigated organisms (2,200), lichens represent 4.7% of the biodiversity of the study site. In spite of the low number of protected lichen species in Hungary (8, most of them terricolous), 3 legally protected lichen species occur here (Cladonia arbuscula, C. mitis, C. rangiferina). Lecanora bolcana is new to Hungary, and rare species, like Evernia divaricata, Leptogium tenuissimum, and Rimularia insularis were also found. Three microfungi are also listed. Keywords: biodiversity, Evernia divaricata, Hungary, Leptogium tenuissimum, lichen-forming fungi, Fekete Hill, Rimularia insularis, Szentbékkálla.