DURING the course of an investigation made by the Central Veterinary Laboratory into the incidence of leptospiral infection in small wild mammals a number of strains were recovered. Most of these apparently belong to the hebdomadis group, but one strain, W. V.14, from a water vole, was serologically in the autumnalis group. It was finally identified in Amsterdam as L. erinacei auriti as shown in Table 1. An apparent relationship to grippo-typhosa and butembo in cross-agglutination tests was not confirmed by absorption tests.