In electrophoretic spectra of hemoglobins of Chironomus species of plumosus group, 3 groups of fractions are arbitrarily identified: fast fractions (mobility of 0.85 and higher), fractions with intermediate mobility (0.58–0.83), and slow fractions (mobility of 0.43 and lower). The most unstable turned out to be the fast fractions; their protein content increased considerably at storage and repeated freezing–thawing of samples. Fractions with the intermediate mobility are the most numerous, have a high specific amount according to the protein content and a high peroxidase activity. The slow fractions in the majority of species were characterized by a low peroxidase activity and high protein content. An interspecies comparison of electrophoretic spectra of hemoglobins has shown that the species that are the most tolerant to oxygen deficiency have the slow fractions with the lowest mobility. The obtained data have allowed suggesting that that the identified groups of hemoglobins are functionally heterogeneous: (1) the fast fractions with mobility of 0.85 and higher are products of degradation of hemoglobins with a higher molecular mass; (2) fractions with intermediate mobility (0.58–0.83) have a high affinity to oxygen and provide its utilization at its very low concentrations in water; (3) the slow fractions with mobility of 0.43 and lower have a high mol. mass and perform the buffer function preventing disturbance of the acid-base equilibrium of internal medium at anaerobiosis.