The aim of this study was to characterize beta-globin gene micro-haplotype polymorphisms (frameworks) associated with a beta-thalassemia mutations common in Northern Thailand using a direct DNA sequencing method. A total of 11 beta-thalassemia major patients homozygous for the codon 17 (A-->T) mutation admitted to Chiang Mai University Hospital were examined. All 22 alleles were found to contain the Asian framework 3A. The homogeneity of the framework associated with the codon 17 (A-->T) mutation indicates a relatively recent origin of the codon 17 (A-->T) mutation. Similar studies in other East Asian populations may provide information concerning the origin and the migrational spread of this beta-thalassemia mutation.