Globin prepared from adult hemoglobin of the rhesus monkey was separated into α and β polypeptide chains by the countercurrent distribution method. The α and β polypeptide chains were digested with trypsin. All the tryptic peptides were isolated and purified by column and paper chromatography. The amino acid compositions and the N‐terminal amino acid of these tryptic peptides were analyzed.According to the results thus obtained, the α and β polypeptide chains of adult hemoglobin of the rhesus monkey are respectively composed of 141 and 146 amino acid residues just as those of human hemoglobin. However, it is presumed that there exist at least four amino acid substitutions in the a polypeptide chain and eight in the β polypepti