Early life stress is one of non-genomic factor that influences offspring phenotype, growth and behaviors. In mammals, glucocorticoids exposure during the embryonic development cause epigenetic programming of the body where methylation imprints are established. Relevant studies are missing in avian species. Corticosterone (CORT) is a predominant glucocorticoid in the plasma of birds. It is reported to be deposited in the avian eggs, and has been measured in the egg of a variety of avian species including domestic chicken, quail, and canary. The effect of CORT on aggressive behavior and its relation with Serotonergic system and epigenetic programming is not been studied in chickens. In this study, we first investigated differences in egg deposition of CORT and embryonic expression of CORT metabolic enzymes between slow and fast growing broiler chickens. Secondly, we used a model of in ovo injection of CORT and investigated the effect of CORT on growth, aggressive behavior and its relation with serotonergic system and epigenetic modification. Finally, we investigated the effect of in ovo injection of CORT on ovary functions in the chicken.