1. 1. Through the use of isoelectric focusing and peptide analysis, the hemoglobins of Przewalski's horse, Equus przewalskii and the domestic horse, E. caballus have been compared. 2. 2. Przewalski's horses have two separate α-globin chain polymorphisms similar to domestic horses. Each hemoglobin phenotype could be accurately determined by isoelectric focusing. 3. 3. Confirmation of the electrofocusing hemoglobin determinations was made by comparison to amino acid composition analyses of purified tryptic peptides and by analysis of the rare hemoglobins phenotypes observed in a family of Norwegian trotting horses. 4. 4. Hemoglobin genotypes of fifteen Przewalski's horses were determined and inheritance of hemoglobin haplotypes has been observed.