The occurrence of helminth parasites and leptospires from the Long‐tailed field mouse,Apodemus sylvaticus, the Bank vole,Clethrionomys giareolusand the Short‐tailed vole,Microtus agrestishas been studied from four woodland areas in Surrey. The composition of the helminth fauna of these rodents, particularlyA. sylvaticusandC. giareolus, differs from that of previous studies carried out in the British Isles in consisting largely of cestodes and fewer species of digeneans and nematodes. On the other hand the degree of infection of the rodents with nematodes as in the case ofA. sylvaticusinfected with the trichostrongylidNematospiroides dubiusand theoxyuridSyphacia stromaand ofC. giareoluswith thecap‐illaridCapillaria muris sylvaticiis greater than the cestode and digenean infections and is probably linked with the monoxenous nature of the nematode life cycles.Differences in the number, incidence and degree of infection of mice and voles with species of helminths is undoubtedly linked with differences in the feeding habits of the respective hosts but the present study has also confirmed that infection levels in both leptospires and helminths are influenced by the age/sex relationships of the host together with season and habitat. The relationship between the distribution of rodents infected with leptospires and some helminths suggests similarities in the mode of their transmi