The present study concerns with some biological aspects in chicks fed irradiated animal protein by-products. Feeding chicks with irradiated blood, fish or meat-bone meal induced insignificant changes in body weight during the period of investigation. However, some occasional and sporadic differences appeared in body weight between control and experimental groups of chicks. No treatment – related effects of biological significance were induced on relative, absolute and dry weights of stomach, gizzard, heart, lungs, liver, spleen and kidney due to the ingestion of irradiated protein by-products. Also, the same tendency was remarked among the groups of birds with regard to length and width measurements of left tibia. Mean hematology data were generally consistent within normal ranges for controls and those received the irradiated protein by-products. The overall results suggest that irradiated animal protein by-products could be mixed with other food ingredients in poultry rations without deleterious or harmful effects.