EN
The authors give an account of the results of their investigations on the helminthofauna of the rats Rattus norvegicus, caught in the Warsaw area and suburbs. 150 rats were examined and 6 species of parasites found. The authors confirm after Obitz (1933) a permanent occurrence of Trichosomoides crassicauda in Poland and emphasize an increase in infections of rats with endoparasites in the Warsaw area, in the period 1933-1958.