The human gamma-, delta-, and beta-globin genes are located within a 30-kilobase (kb) region of DNA, of which only 20% represents the globin genes. We have attempted to define the nature of flanking and intergenic sequences by isolating recombinants containing the human epsilon, both gamma-, or the 3' end of the beta-globin gene from a bacteriophage library of cloned human DNA. Comparison of these recombinants and a recombinant containing the delta- and beta-globin genes (H beta G1) has provided the following results. The epsilon-globin gene is located 14 kb 5' to the G gamma gene. DNA sequence homology between the region containing the two G gamma genes and the delta nd beta gene region is limited to only a few hundred nucleotides which include the globin coding sequences. Repetitive DNA sequences have been found in the region 3' to the beta-globin gene. Sequences located adjacent to the beta-globin gene are repeated in the globin gene region. A repetitive DNA sequence more than 3.2 kb long is repeated frequently in the human genome but is not repeated in the globin gene region in the clones examined.