Illustrated keys are presented for identification of female mosquitoes of 19 genera occurring in Southeast Asia, five subgenera of Culex, and 16 commonly encountered species of Culex (Culex), nine of which have been incriminated as vectors of Japanese encephalitis. Because members of the Culex vishnui subgroup, which includes some important vectors, are notoriously difficult to identify as adults, separate adult and larval keys are provided. Notes and distribution on individual species are included.