Two strains of epizootic hemorrhagic disease virus (EHDV), New Jersey (NJ) and Kentucky (KY), of deer were biologically transmitted between white-tailed deer, Odocoileus virginianus, by Culicoides variipennis. The KY strain, isolated from C. variipennis collected during an epizootic in deer, was identified as EHDV by serological tests. Deer exposed to the KY or the NJ strains of EHDV developed an acute hemorrhagic disease; most deer died 6 to 13 days after infection. Sheep inoculated with EHDV developed no clinical signs of disease.