This study aimed to confirm that poultry products packed at poultry processing plants have already been contaminated with Listeria monocytogenes and that poultry products contaminated with L. monocytogenes are derived from broiler flocks infected with L. monocytogenes. L. monocytogenes was isolated from 16.8% (58/345) of chicken breast products and 2.3% (8/345) of chicken liver products. In contrast, L. monocytogenes was isolated from the pooled cecal content sample from only 1 (4%) of 25 flocks and was never isolated from any pooled dropping samples collected from 25 farms. The results of our study indicate that cecal content does not seem to be an important source of L. monocytogenes in poultry products.