A total of 4,111 chicken sera collected from 1985 to 1995 at 137 farms in 36 prefectures were subjected to an enzyme-linked immunosorbent assay (ELISA) to test for antibodies against turkey rhinotracheitis (TRT) virus. The antibodies to TRT virus were detected in the chicken sera collected from 1988 to 1995, but the antibodies to TRT virus were undetectable in the sera of chickens collected before 1987. The antibody positive rates each year ranged from 2.2% (1988) to 54.2% (1995). Recently, the TRT virus has spread over the flocks of commercial broiler and layer chicken throughout the country. The serological findings indicated that the TRT virus had invaded the chickens before 1988, and has been widespread thereafter in Japan.