The aim of this study was to investigate the presence of antibodies to ALV-J in broilers and broiler breeders. For this, 5 broiler units and 1 broiler breeding unit in the Marmara region were visited. Seventy 4-6-week-old chicks from the broiler units, consisting of 14 chicks from each broiler unit, were selected. Seventeen chickens from the broiler breeding unit were also selected. The chicks from the broiler units were necropsied and all internal organs were checked for the presence of tumors. Blood sera collected from all animals were analyzed for the presence of antibodies to avian leukosis virus subgroup-J (ALV-J) by a commercial ELISA (IDEXX). Growth retardation, depression, diarrhea and respiratory disorders were seen in chicks from the broiler units. No tumors were observed in the internal organs. However, pseudomembranes on the liver of 3 chicks and Gumboro-like lesions in the bursa of Fabricius in 5 chicks were seen. No antibodies to ALV-J were detected in any of the broiler chicks' sera. However. antibodies to ALV-J were detected in 13 (76%) of the 17 broiler breeders, which indicates the necessity to apply eradication programs for ALV-J in breeding flocks in Turkey.