β-Thalassemia, an autosomal recessive disorder, shows considerable clinical heterogeneity, phenotype varying from life threatening severe anemia and transfusion dependency to near normal, asymptomatic condition. More than 300 mutations, both in and around beta globin gene [1,2] are attributed to this phenotypic spectrum. β-Thal has been shown to have considerable presence in the Indian subcontinent, espe- cially in the western, northern and north-eastern regions. Based on the genotypic information from these regions, 5 major mutations have been identified that are believed to account for more than 80% of the patients. However, occurrence of β-thalassemia in the larger part of the land mass of India is only now being realized [3,4]. Therefore the present study has been undertaken to have an estimate of the mutation profile of the β-globin gene, its LCR and α globin gene defects and XmnI polymorphisms leading to β-thalassemia to enable us to define their modulatory role in the heterogeneity and diversity of the β-thal pheno- types in cases from the eastern region of India (Eastern Uttar Pradesh and adjoining states of Bihar, Jharkhand and Chhattisgarh).