The main aim of the research was characterization of nematode species isolated from Melolontha sp. larvae. European cockchafer grubs were collected from the forest territory of Krasnystaw, Kozienice, Opoczno, Brzeziny, from areas with different light conditions, humidity and temperatures. The isolated nematodes were described based on light and scanning electron microscopy, supplemented with SSU rDNA (ribosomal deoxyribonucleic acid) sequence data. The obtained results revealed that grubs were infected by the following nematode species: Diplogasteroides magnus, Koerneria sp. and Rhabditis sp. Most of the grubs infected by nematodes were collected on tree-covered areas, where the surface was shadowed and humidity was the highest.