A quiet revolution in the field of immunodiagnosis is underway. Its objective is to provide simple and accurate methods for making a laboratory diagnosis of infectious diseases, endocrinopathies, and immunodeficiencies. Monoclonal antibody technology will provide unlimited quantities of antisera with defined and stable antigenic specificity. These antibodies will be incorporated into new serologic methods, namely enzyme-linked immunosorbent assay and agglutination tests. Unlike traditional methods, these new procedures are easily adaptable to kit form and consequently will likely become available for routine use in clinical situations in the near future.