Oligodeoxyribonucleoside methylphosphonates which are complementary to the 5' end, the initiation codon regions, or the coding regions of rabbit globin mRNA were synthesized. These oligomers were shown to interact with their complementary mRNA binding sites by their ability to serve as primers for reverse transcriptase. In several cases, the priming efficiency of the oligomers was enhanced when the oligomer was preannealed with the mRNA. This behavior correlates with the predicted secondary structure of the mRNA and suggests that some oligomer binding sites occur in hydrogen-bonded stem regions of the mRNA. Methylphosphonate oligomers inhibit translation of globin mRNA in reticulocyte lysates. Inhibition is due to the interaction of the oligomers with mRNA. The extent of inhibition is affected by the sequence and chain length of the oligomer, the location of the oligomer binding site on the mRNA, and the secondary structure of the binding site. Oligomers which bind to the 5' end and initiation codon regions of beta-globin mRNA inhibit both alpha- and beta-globin synthesis whereas oligomers which bind to the coding region of alpha-globin mRNA or the coding region of beta-globin mRNA inhibit translation of their target mRNA in a specific manner. Oligodeoxyribonucleoside methylphosphonates inhibit globin synthesis in rabbit reticulocytes. The effects of various oligomers on cellular globin synthesis are similar to those in the lysate system and suggest that the conformation of globin mRNA is the same in both systems during translation.