Hookworm infection is a major parasitic cause of morbidity in the developing nations of the tropics. Development of a genetically engineered vaccine would be a useful tool in the control of this infection in highly endemic areas. Recombinant polypeptides belonging to the Ancylostoma secreted protein (ASP)-1 family have shown promise for reducing hookworm burdens after larval challenge infections in mice. Typically, these polypeptides are expressed in Escherichia coli and administered as an alum precipitate. Vaccine protection is antibody dependent. It is anticipated that a cocktail of different recombinant hookworm antigens may be required in order to effectively prevent heavy hookworm infections and disease. The progress of this work has been hampered by the absence of both a convenient laboratory animal with which to study hookworm infections resembling human infection, as well as the lack of easy availability of native hookworm antigens. In addition, useful human serologic correlates of antihookworm immunity are still poorly defined.