Serum samples from 379 adult cows with lowered fertility farmed in the Rio de Janeiro region of Brazil. They were examined for Leptospira antibodies. A questionnaire was completed for each herd. Antibodies were detected in 46.9% of these cows, mainly to serovar hardjo. Main risk factor associated with seropositivity was co-grazing with other species, mainly pigs (OR = 3.17; p<0.04). Absence of or infrequent veterinary assistance (OR = 1.74) has also been suggested to be associated to the overall seroprevalence to leptospirosis. We suggest that a successful control programme for bovine leptospirosis should include a complete investigation of herd management practices, which could influence in the occurrence of the infection.