Outbreaks of West Nile virus (WNV) infection have occurred sporadically in Europe, apparently due to the migration of infected birds and the subsequent establishment of a transmission cycle involving culicine and anopheline mosquitoes. Both human and equine species become infected, but are considered as dead end hosts since they play an insignificant role in the maintenance of the cycle. Following the introduction of WNV into the United States in 1999 it is increasingly apparent that the virus has an extraordinary ability to infect a very broad range of arthropod species. Here we consider the potential for British mosquitoes to transmit WNV in the event that it is introduced into the UK.