ackground:.β-thalassemias constitute a major health problem in mediterranean countries. Impaired glucose tolerance and diabetes mellitus are observed complications in patients with thalassemia .However, the mechanisms leading to diabetes are still poorly understood. The H63D polymorphism,is the second variant of hemochromatosis HFE genethat cause hemochromatosis Objective: to asses the frequency of H63D gene polymorphism and its relationship to development of prediabetes and diabetes mellitus in β -thalassemia patients Method: A case control study was carried on 50 β-thalassemia patients who were registered in and followed up at hematology outpatient clinic; Pediatric department, Zagazig University with age range from 6 to 18years and 50 age and sex matched healthy control through a period of 6 months. Results : our study showed that 32% of patients had normal glycemic state, 52% had prediabetes and 16% were diabetic P