The effect of glutamine on the structure of the intestinal mucosa, after suffering any damage is raising interest due to the fact that this amino acid is the main metabolite which nourishes the enterocytes. Yet, the mechanism that promotes proliferation of the intestinal cells is not well known. It might be related with two events: increase of Na+/H+¨ exchange at the plasmatic membrane and increase of ornithine descarboxylase specific activity. Glutamine is also able to raise gene transcription, by increasing the activity of kinase protein which activates mitogenesis (Blikslarge et al., 1997). Chick’s weight is determinated by eggs initial weight. Older breeders produce bigger eggs which become chicks with higher weight at eclosion moment. In other words, higher consumption levels of protein at the beginning of laying, provide better albumen quality which becomes thicker, delaying oxygen exchanges, the absorption of yolk sac and embryo uptake of vitamins through egg yolk (Brake, 1995). As the embryo produces 90% of its energy from fat acid oxidative process, oxygen deficit would slow lipid oxidation and embryo development. The purpose of this study was to evaluate the development of the intestinal mucosa of chicks at 7 days of age, proceeding from breeders of different ages and fed with and without glutamine supplement.