Rodents are a minor element in the Early Eocene terrestrial fauna from the Eureka Sound Group of Ellesmere Island. Nevertheless, at least five taxa can be recognized, all members of the family Ischyromyidae. Two are paramyines, of which one is described as Paramys hunti, sp. nov. Three of the rodents are microparamyines, Microparamys bayi, sp. nov., and two species of the new genus Strathcona, S. minor, sp. nov., and S. major, sp. nov. The paramyines are Holarctic in distribution in the Early Eocene, but the microparamyines are known only from North America and Europe. The Arctic Microparamyinae provide the first clearly documented case for an early Cenozoic mammalian taxon having a North American origin and later dispersal into Europe across a North Atlantic terrestrial biogeographic province.