Aedes vexans (Meigen) mosquitoes were given access to 2- to 4-day-old chickens inoculated with 103.0 CID50s/ml West Nile Virus (WNV) at 1 day old. Mosquitoes were given access to chickens at different intervals after inoculation to make certain that blood meals were of varying virus titers. No differences occurred in infection rates of Ae. vexans and Culex pipiens (L.) fed on the same WNV viremic chicken. Infection rates of Ae. vexans were higher when fed on chickens with viremias of 6.0 log10 WNV PFUs/ml or higher than they were in mosquitoes fed on chickens with viremias below 6.0 log10 WNV PFUs/ml. Dissemination rates were similar in Ae. vexans 14 and 21 days post blood feeding (PBF). Likewise, transmission rates were similar in Ae. vexans 14 days and 21 days PBF. This indicated that, under laboratory conditions, Ae. vexans is a competent vector of WNV.