Species diversity and trophic structure of nematode communities from different types of forests of the “Codrii” Forest Reserve located in the central part of Moldova have been studied. A total of 144 species of soil nematodes belonging to 97 genera and 11 orders were identified. Most of nematode species are bacterivores - 52 species (36.2% from total number of species), followed by plant feeders - 26 species including mainly ectoparasites (18%), omnivores - 26 (18%), predators - 20 (13.8%), fungivores - 17 (11.8%) and substrate ingestion - 3 (2.2%). In the nematode communities bacterivores and omnivores were dominant both qualitatively and quantitatively. The highest species diversity was revealed in beech forest (65 species) than in lime-ash (49) and maple-hornbeam (42). In the natural and protected forests the high diversity of predators, rare and endemic species is noted.