Entomological investigations of the possible mosquito vectors of the yellow fever epidemic on the Jos Plateau, Nigeria, were carried out between 27 October and 15 November 1969.Of the 5 species of Aedes (Stegomyia) collected, Ae. luteocephalus was the most abundant in human-bait captures. Ae. aegypti, Ae. africanus, and Ae. vittatus were collected in low numbers. The aegypti larval index in the areas investigated was very low and the species was not considered to be the primary vector in the epidemic. Ae. simpsoni larvae were abundant, but no adults were collected on human bait.Six isolates of 5 different arboviruses were obtained: yellow fever from damaged Stegomyia sp.; dengue 2 from damaged specimens, probably all Ae. luteocephalus; Zika (2 isolates) from Ae. luteocephalus; Bwamba from Anopheles funestus; and a Nyando-group virus from An. gambiae.