Background: Repeated blood transfusion causes a lot of complications in the body specially iron deposition in different organs in the body. Objective: Investigating the changes which occurred in the human body blood parameters on repeated blood transfusion. Subjects and methods: This study was performed at outpatient clinic, Faculty of Medicine, Al-Azhar University Hospital (Assiut). The patients were forty patients already diagnosed as thalassemic major and exposed to repeated blood transfusion and the following parameters were measured (oral glucose tolerance, plasma glucose level, plasma insulin level, C- peptide level, lipase level, serum iron, total iron binding capacity and serum Ferritin). Results: The study showed that hemosidtherosis affected the level of serum lipase which decreased in thalassemic patients as a model of hyperplastic anemia. Also, C-peptide level decreased in those patients more than control. This indicated that the pancreatic functions were affected by iron deposition. Also, serum iron and serum ferritin increased which led to decrease in the level of total iron binding capacity which caused by decrease in Hb level. Conclusion: Blood glucose level increased significantly in thalassemic patients while insulin level decreased in them. Serum Ferritin level was increased in thalassemic patients where the hemoglobin decreased. Serum lipase and C-lipase decreased in thalassemic patient