Serum samples obtained from 922 apparently healthy and unvaccinated cattle were used to determine the serological prevalence of bovine leptospiral infections in south Marmara region of Turkey. The sera were screened for the presence of leptospiral antibodies using four serovars of Leptospira interrogans (hardjo, grippotyphosa, pomona, and icterohaemorrhagiae) in the microscopic agglutination test (MAT) at 1/100 dilution. Thirty-one (3.4%) of the cattle examined had leptospiral antibody titres of 1/100 or higher to one or more of the test antigens. The prevalence rates of antibodies to individual serovars were hardjo (2.8%), grippotyphosa (0.4%), and pomona (0.2%). Moreover, the seroprevalence of hardjo infection increased with the age of animals. In conclusion, serovar hardjo infections were determined to be more common leptospiral infections in cattle in south Marmara region of Turkey.