8 strains of 4 arboviruses were isolated from blood and organs from 775 birds captured at Mitchell River Mission in 6 collections from October 1964 to March 1967. 3 strains of Ross River virus (from Grallina cyanoleuca, Microeca fascinans and Poephila personata) and 1 strain of Corriparta virus (from Charadrius melanops were isolated in March-April 1965; 3 strains of a Group B virus (from Centropus phasianinus) and 1 strain of Kunjin virus (from Oriolus flavocinctus) were isolated in March-April 1966. The Group B virus was found antigenically distinct from those previously isolated in Australia, and has tentatively been named Alfuy virus. No viruses were isolated from birds collected during the dry seasons. Serological tests on bird serum or blood gave additional evidence of infection with Group B arboviruses, Sindbis, Corriparta and Koongolg Group viruses. The isolation of Ross River virus from birds was at some variance with the results of previous serological surveys and is discussed.