Metastrongyloid nematodes are cardiopulmonary parasites affecting domestic cat (Felis catus) and wildcat (Felis silvestris) populations throughout Europe. Terrestrial snails and slugs may act as intermediate hosts of these parasites. The present study reports on the identity of the intermediate hosts in areas in Greece where domestic cats and wildcats occur in sympatry. In order to survey the prevalence and expansion of the nematode parasites, an accurate identification of their intermediate snail and slug hosts is important. Yet, detecting the presence of parasites in the intermediate hosts requires a destructive approach by which a morphological identification of the intermediate hosts becomes difficult. Moreover, juvenile gastropods often lack their species-specific characteristics. Therefore, DNA barcoding is used in addition to the morphological identification. DNA sequences used for species identification include the universal COI gene fragment (cytochrome c oxidase subunit I), the 16S ribosomal RNA and the ITS2 gene fragment (internal transcribed spacer 2). Hitherto, infected snails and slugs included Eobania vermiculata, Helix lucorum, Cornu aspersum, Ambigolimax valentianus, Limax cf. conemenosi and Tandonia cf. sowerbyi. These species are efficient colonizers of new areas, and have been introduced in several parts of Europe. Therefore, there are concerns about the possible further spread of the nematode parasites they can carry, the more so as in its first stage the survey provided new occurrence data on three metastrongyloid species, viz. Aelurostrongylus abstrusus, Troglostrongylus brevior, and Angiostrongylus chabaudi.