Immunomodulators are substances that act in the immune system providing, increase of the organic answer against microorganisms, including virus, bacteria and protozoa, by inducing the production of interferon and its inducers. There are a lot of situations in veterinary medicine where it is usefull to potencialize the immune response of individuals, mainly when is desired to increase the resistance to infections and the treatment of immunossupressing or multifactorials infectious diseases. In veterinary medicine some of more used immunomodulators are interferons and interferon inducers, interleukines, Baccilus of Calmett-Guerin (BCG) and its derivated, Propionibacterium acnes (Corynebacterium parvum), mixed bacterial vaccine, PIND-ORF, Phosprenyl, Quillja Saponis, Bordetella pertussis, avridine and the levamizole. The present review the available scientific literature, regarding the use of different immunomodulators in the prophylaxis and in the therapeutics of infectious diseases in domestic animals.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)