Experiments on broiler chicks and laying hens have indicated that increased drug loads (the prolonged oral use of oxytetracycline hydrochloride in a dose of 50 mg/kg or the single administration of its long-acting formulation--nitox in a dose of 200 mg/kg) lead to the accumulation of residues in the poultry flesh, by-products, and eggs even provided that the poultry exposure schedule before slaughtering is kept. The highest levels of the antibiotic are detectable at the site of injection and in the eggs after injection of nitox, a long-acting formulation of tetracycline. The detection of the residues of the antibiotic in the poultry flesh, by-products, and eggs may be associated with the development of cytotoxic effects and with the reduced functional capacities of the organs that are responsible for the detoxification and excretion of medicinal xenobiotics.