Biotinylated Anti-Avidin andBiotinylated Anti-Streptavidin antibodies have been used extensively as signal amplification reagents in immunohistochemistry, in situ hybridization, microarray assays, ELISA assays, and Western blots. Our Avidin and streptavidin antibodies are produced in goats using highly purified avidin or streptavidin and IgG fraction was isolated by affinity chromatography. Test of cross reactivity shows that our Anti-Avidin does not bind streptavidin and Anti-Streptavidin does not recognize avidin suggesting that their antigenic-binding sites are different for these twoBiotin binding proteins. These antibodies allow significant signal amplification in a variety of applications. The ability of binding avidin or streptavidin via eitherBiotin binding sites or through antigen binding sites, makes theseBiotinylated antibodies unique reagents. These antibodies can be used either as part of a preformed complex or in sequence to amplify fluorescent signals. In a sequential reaction, the target is first labeled with fluorochrome-conjugated avidin or streptavidin, followed by incubation withBiotinylated Anti-Avidin orBiotinylated Anti-Streptavidin. This is followed by a second layer of fluorochrome-conjugated avidin or streptavidin reagent. This multi-layered approach introduces more fluorochrome at the target site and can provide a several fold amplification over a single layer approach.