Delta-Beta thalassemia is an unusual variant of thalassemia caused by large deletions in the β globin gene cluster involving δ- and β-globin genes. The mutations are characterized by high fetal hemoglobin with significant phenotypic diversity. Routinely used diagnostic tests targeting point mutations and small insertions, deletions of the β-globin gene are not suitable for detection of large deletion mutations. This is overcome by either direct globin chain synthesis analysis or beta-cluster gene analysis using different methods. In the current study, we use direct globin chain analysis to diagnose a family with δβ-thalassemia using high resolution mass spectrometry.