These keys and illustrations have been prepared in response to many requests. They concern only those species of Anopheles which have been recorded as occurring in West Africa south of the Sahara Desert as far as the equator. Much of the material has been derived from the recent Monograph by the late Dr. A. M. Evans on the Anophelines of the Ethiopian Region published by the British Museum in 1938. Personal acquaintance with the Anophelines of East and South Africa and examination of the specimens in the collection of the Department of Entomology of the London School of Hygiene and Tropical Medicine have assisted in the preparation of the keys.