Aedes canadensis was shown to be a vector of La Crosse (LAC) virus in Ohio through isolation of LAC virus from field-collected specimens, infection of 54 of 72 (75%) individuals when fed on viremic suckling mice and transmission of LAC virus by 29 (54%) of infected individuals. Frequent identification of Ae. canadensis as a human biting species implicates it as an auxiliary vector of LAC virus to man. A possible regional association in Ohio of Ae. canadensis and Type C LAC virus is discussed.