The South American Lungfish has only one hemoglobin component. The complete amino-acid sequence of this hemoglobin is presented. A large quantity of carbonate dehydratase from the lungfish erythrocytes was also isolated. The carboxymethylated chains, obtained by separation of globin on DEAE-Sephacel, were submitted to tryptic digestion and chemical cleavage. The isolation of tryptic peptides was achieved either by Dowex-50 chromatography or by high performance liquid chromatography. The alignment of peptides was performed by homology with the previously established sequences of the carp and goldfish hemoglobins. The overlapping peptides confirmed this sequence. The alpha chains have 143 residues, the beta chains 147. The relation between the primary structure and the physiological properties of lungfish hemoglobin are discussed.