Earlier studies on differences in moose (Alces alces) chromosome sets concerned only European (Scandinavia, Finland, the Volga region, and western Siberia) and American (the United States and Canada) forms. The first group had a 68-chromosome set, and the second group, a 70-chromosome set. These differences were considered interspecies chromosomal polymorphism. However, the chromosome number in A. alces living in eastern and northeastern Siberia remains unknown, although these data are important for elucidation of the geographical variation of karyotypes of moose from genus Alces. Four moose from different regions of Sakha were studied. It was found that their karyotypes contained 70 chromosomes; i.e., they were similar to the American form. These data indicate a strong differentiation within the species. Two chromosomal forms can be distinguished: the European one (2n = 68) living in Europe and western Siberia and the American one (2n = 70) living in North America, the Far East, and eastern Siberia. The existence of two forms is confirmed by data on their morphology, sound signals, electrophoretic mobility of proteins, and differences in nutrition. These results indicate that long-term isolation of European and American moose led to the high divergence between these two forms; therefore, they can be considered different species.