Snowshoe hare (SSH) virus was isolated from one pool of 54 unengorged adult female Aedes nigripes mosquitoes, among a total of 4,466 mosquitoes of 4 species collected throughout the Yukon Territory, Canada during the summer of 1983. Another SSH virus strain was isolated from 1 of 22 pools of Aedes sp. larvae collected near Whitehouse during April 1983. During 12 summers from 1972 to 1983, 54 SSH strains and 4 Northway (NOR) virus strains were isolated from 136,854 adult mosquitoes of 7 species. An additional 4 SSH strains have been recovered from 453 pools of Aedes sp. larvae collected during the springs of 5 years.