Splicing mutations are common causes of -thalassemia. Some splicing mutations permit normal splicing as well as aberrant splicing, which can give a reduced level of normal -globin synthesis causing mild disease (thalassemia intermedia). For other mutations, normal splicing is reduced to low levels, and patients are transfusion dependent when homozygous for the disease. Development of therapies for -thalassemia will require suitable mouse models for preclinical studies. In this study, we report the generation of a humanized mouse model carrying the common IVSI-110 splicing mutation on a BAC including the human -globin (^hu-globin) locus. We examined heterozygous murine -globin knockout mice (^muth-3/+) carrying either the IVSI-110 or the normal hu-globin locus. Our results show a 90% decrease in ^hu-globin chain synthesis in the IVSI-110 mouse model compared to the mouse model carrying the normal ^hu-globin locus. This notable difference is attributed to aberrant splicing. The humanized IVSI-110 mouse model recapitulates accurately the splicing defect found in comparable -thalassemia patients. This mouse model is available as a platform for testing strategies for the restoration of normal splicing.