The study was designed to investigate the effect of different doses and different durations of ferrous gluconate drug administration on some blood criteria, using 36 males of rats. The animals were divided into four main groups (9 males for each group), the first group control and the other three groups were orally intragastric administrated with (50,75,100) mg/kg bw for three periods (4,6,8) weeks .The blood samples were collected to measure the haematological criteria that include Red Blood Cells count (RBCs) , blood haemoglobine (Hb),Packed Cell Volume(PCV),Mean Corpuscle Haemoglobine Concentration (MCHC), Mean Corpuscular Haemoglobine (MCH) and Mean Corpuscle Volume (MCV). Results of this study revealed, that ferrous sulfate administration causes a significant elevation for all haematological parameters which proportionally increased with the dosage levels and dosage durations. It was also observed a significant effect of interaction between different doses and periods on most haematological parameters except MCH and MCHC. All results compared with control group and between treated groups, and had no signefecant effect in ALT, AST, bilirubin, creatinin. The results suggested that the administration of ferrous glugonate drug in high dosing level and long durations may causes defect in haemopoesis especially erythropoiesis that indicated by increased blood parameters level rather than treatment of iron deficiency anemia because of iron supply increase.