Seven hundred seventeen cattle, over the age of six months in the South Marmara Region (Bursa, Bahkesir and Canakkale) were tested for the presence of Bovine leukemia Virus (BLV)-antibody with ELISA. Blood and milk samples were taken from 362 and 355 cattle, respectively. Totally, sixty-nine cattle (9.62%) were found to be carriers of antibodies against BLV-gp 51 antigen. The BLV infection rate was found to be 13.25% and 5.91% in the sera and milk samples tested, respectively. The infection rate were determined to be 14.19% in Bursa and 3.52% in Bahkesir, but BLV seropositive cattle were not found in Canakkale. It was observed that the highest infection rate was in the Karacabey provincial region of Bursa.