Powassan virus was isolated from 2 pools of ticks (1 unidentified, the other Ixodes cookei) removed from 2 Marmota monax live-trapped in northern St. Lawrence County. Powassan virus was also isolated from tissues taken from the same 2 animals. Another strain of POW virus was recovered from the brain of a sick gray fox found in Broome County 200 miles to the south in New York State. The 2 tick strains were compared antigenically with the proto-type POW strain and were found to be antigenically similar.