Within the boreal zone, there are about 50 native mammalian herbivore species that belong to the orders Artiodactyla, Rodentia, and Lagomorpha. Of these species, 31 occur in the Nearctic and 24 in the Palaearctic. Only six species occur in both regions. Species of the family Cervidae have probably been, and still are, the most important group for man, as they provide both meat and hides. Pelts from squirrels, muskrats, and hares were commercially harvested at the beginning of the century, but have less value today. The semi-domestic reindeer in the Palaearctic produces meat and hides on a commercial basis. It is also used for milking, to a limited extent, as is the semi-domestic moose in Russia. The Siberian musk deer is used for its musk and is raised in captivity in China. All species heavier than 1 kg are utilized by man, those with a body mass in the range 1 kg - 1 hg are sometimes used, and species lighter than 1 hg are rarely used. Here, we review the numerical fluctuations in terms of periodicity and amplitude, based on an extensive data set found in the literature, especially from the former Soviet Union. Current understanding of the underlying factors behind the population fluctuations is briefly reviewed. Management and conservation aspects of the mammalian herbivores in the boreal zone are also discussed. We conclude that there is a challenge to manage the forests for the mammalian herbivores, but there is also a challenge to manage the populations of mammalian herbivores for the forests.