This report is concerned with the evaluation of hematological parameters and of both relative (%) and absolute (mean pg/cell) quantities of the abnormal Hemoglobin (Hb) Hasharon in 53 heterozygous carriers and 7 double heterozygotes for Hb Hasharon and β-Thalassemia from 43 apparently unrelated families living in the province of Rovigo (northern Italy). Biosynthetic studies are also reported. The data strongly suggest the presence of an α-thalassemia-2 determinant closely linked to the αHasharon-chain locus. Selective advantage of heterozygotes carrying such α-haplotype would explain the relatively high frequency of Hb Hasharon (0.23%) in northeastern Italy, a past-endemic malaria region. The interaction between Hb Hasharon and β-Thalassemia results in preferential decrease of the abnormal Hb level.