Heterakis spumosa Schneider, 1866 is a typical and widespread parasite of Rattus sp. Recently published reports on its presence in rodents other than rats and house mice (e.g. Apodemus agrarius and A. flavicollis) may suggest acquisition of new host or the existence of two distinct species parasitising within the subfamily Murinae in Europe. The first aim of our study was to examine the taxonomic status of H. spumosa isolated from three host species (Rattus norvegicus, Apodemus agrarius and A. flavicollis) by analysing the partial sequence of small subunit (18S) of ribosomal DNA (rDNA). The second aim was to investigate the pattern of occurrence of H. spumosa within the two species of Apodemus. As a result of partial sequencing of 18S rDNA we obtained three sequences, 977 bp (A. agrarius), 867 bp (A. flavicollis) and 873 bp (Rattus norvegicus) long. Multiple alignment showed that the nucleotide composition of DNA from all the hosts was identical, which may suggest that the nematodes isolated from the three host species are conspecific. Parasitological and statistical analysis of H. spumosa showed a high prevalence of infection and lower degree of nematodes overdispersion in A. agrarius. Comparative analysis of aggregation level in infrapopulations and metapopulations of H. spumosa indicate that A. flavicollis is not typical host for this species. Our results showed that the factor affecting the presence of H. spumosa is the host's age, but we did not observe any influence of the host's sex or collecting season.