Three new families providing information on the linkage relationships between the 1 and 3 hemoglobin locl are reported. One of the families contains the first reported indivlduals having Hb S and Hb B2in coupling. Analysis of the information found in the literature is compatible with a recombination frequency of 3% between 3 thalassemia and the 5 structural locus. This highly Improbable frequency might be explained by either diagnostic errors or paternitv problems in the pedigrees containing recombinnnts or by the conceivable possibility that certain thalassemia genes increase the probability for recombination in the chromosomal region containing the non a globin genes.