Rabbit and human alpha-globin complementary DNA was synthesized using the primer (dT10)dGdCdC hybridized to globin mRNA with reverse transcriptase, and sequenced using the plus and minus gel sequencing procedure (Sanger and Coulson, 1975; Brownlee and Cartwright, 1977). The complete 3' noncoding region, 89 nucleotides in length, and one third of the coding region of rabbit alpha-globin mRNA have thus been sequenced. These data are compared with the near complete 3' noncoding region sequence of human alpha-globin mRNA obtained in these and previous studies. The two mRNAs are approximately 80% homologous in their 3' noncoding regions, except that the human sequence has an insert of 24 nucleotides. A very similar insert in sequence has been described in human beta-globin mRNA (Proudfoot, 1977).