1. The electrophoretic mobilities of the hemoglobins of 7 taxa of microtines were compared. Microtus oeconomus, M. pennsylvanicus pullatus and M. xanthognatus showed identical 2-band patterns on electrophoresis of their hemoglobins while M. pennsylvanicus tananaensis showed only a single hemoglobin corresponding to the major band of the others. Dicrostonyx rubricatus and D. stevensoni exhibited identical patterns different from the Microtus species. Lemmus sibiricus had a slow hemoglobin component with mobility slightly different from the slow ones of the Microtus species while the fast component appeared the same. 2. Electrophoresis of individual globin chains from hemolysates, purified hemoglobins, and isolated chains indicated a large degree of similarity between the species studied, although there were significant differences in hemoglobin patterns. 3. The minor hemoglobin band in Microtus seems to be the result of a second alpha chain locus as determined from the hemoglobins from hybrids of two subspecies. 4. Salting-out studies indicated differences between hemoglobins that were not detectable by electrophoresis of either whole hemoglobins or isolated chains. 5. M. xanthognathus hemolysate was considerably less soluble than those of M. oeconomus and M. pennsylvanicus pullatus which had essentially the same solubility. 6. The major hemoglobin components of M. pennsylvanicus pullatus and M. xanthognathus were considerably less soluble than either the corresponding unfractionated hemolysates or purified minor components.