Hypozincemic rats fed on flat bread supplemented with different sources of zinc, i.e. natural (20% soy flour) or chemical (ZnO or ZnSO₄ at 8 mg/100 g flour) compared with control (100% wheat flour 72%). Biological evaluation of the experimental rats such as: body weight gain, weight of organs, glucose level, serum alkaline phosphatase, T₃ and T₄, serum testosterone, zinc in serum and zinc in tibia were estimated. The data showed that feeding flat bread supplemented with different sources of zinc increased the body weight and weight of organs. Chemical sources of zinc decreased glucose level compared with natural source. Zinc supplementation increased the level of T₃, T₄ and serum testosterone in rats. Zinc in serum and tibia were increased by zinc supplementation.