This paper confirms the important role of rodents to be maintenance hosts of leptospires. Their role is related to renal carriage and shedding of leptospires into urine, thus contaminating fresh water. Serological and carriage of feral rodents trapped in France were determined by MAT and hap1PCR specific for pathogenic leptospires. In same areas, fresh water samples were analyzed by hap1PCR. The overall seroprevalence was 44% in 649 rodents and was similar regardless of the species. Seroprevalence for leptospirosis is about 20-53% according to species. hap1PCR (516 kidneys) showed that renal carriage was higher in brown rats (34.7%) and muskrats (15.8%) than in coypus (3.3%). hap1PCR demonstrates a significative difference (P-value > 10(-12)) for the renal carriage between the different species: muskrats and rats are more efficient maintenance hosts than coypu but all infect water. Moreover 5/38 water samples associated with human cases were hap1PCR positive and 1/113 in controlled waters.