162 rodents, largely from dairy farms in Taranaki and the Waikato, were examined for evidence of leptospiral infection. 33 (20%) revealed cultural and/or serological evidence of leptospiral infection.L. ballumwas isolated from the kidneys ofRattus norvegicus, R. rattusandMus musculuscollected in Northland, the Hauraki Plains, and in southern Taranaki.L. copenhageniwas isolated from the kidneys ofR. norvegicuscollected in rural rubbish tips near Tirau and Morrinsville. No evidence ofL. hardjoorL. pomonainfections were found among the rodents. Factors contributing to the distribution and incidence of leptospiral infections among rodents, cattle and humans are discussed.