During the 5-year period 1966–1970, a total of 7497 wild mammals of at least 101 different species were collected from 36 locations in Nigeria, Dahomey, and Togo and sampled for virus. The collections were made in five ecologically distinct vegetative zones: high forest, Guinea, Sudan, and Sahel woodland, and the Jos Plateau. Sixteen different virus types, represented by 83 isolates, were recovered, as follows: Arumowot (6 isolates), Bhanja (2), bluetongue type 7 (1), Chandipura (1), Congo (2), Dakar bat (3), Dugbe (1), IbAn 17143 (1), IbAn 33709 (1), Lebombo (1), Mokola (4), poxvirus IbAn 34325 (1), Semliki Forest (1), SudAn 754/61 (53), Uganda S (3), and West Nile (2). Viruses were isolated from Nigeria, the principal area of mammal collecting, and Dahomey, but not from Togo. The possible relationship of these viruses to diseases of man and domestic animals is discussed.