A study of occurrence and geographical distribution of cyst-forming nematodes in monocultural cereal fields and multispecies grassland vegetation in Slovak Republic revealed the presence of two species of Heterodera: H. avenae and H. schachtii. The frequency of occurrence of H. avenae was 37.8 % in cereal fields and 3.3 % in grassland. Cysts of H. schachtii were found only in cereal fields along with cysts of H. avenae, in the western part of country. The occurrence of other graminaceous cyst nematode species was not recorded.