The authors made plant pathological investigations and data collections on grass species important in their seed production areas in Hungary (Keszthely) and Austria (Irdning). The aim was to determine species diversity and dominance relations of plant pathogenic fungal species found on the cultivated grasses of the two ecologically different locations. The present work details only the leaf spot causing fungi and does not inform on rust causing fungi, powdery mildew, and smuts. The work gives information on fungal incidence on grass species, their importance and symptoms of disease caused by Cercosporidium graminis, Ramularia pusilla, Drechslera spp., Bipolaris spp., Mastigosporium spp., Septoria, Ascochyta spp. and Colletotrichum graminicola.