Human and animal sera have been in use for centuries to produce antibodies, providing the medical world with vaccines and other immunochemicals. It is only over the past decade, however, that advances in immunology and monoclonal antibody formation and purification techniques have paved the way for numerous new applications. This area is rapidly proliferating as antibody development is pursued for both diagnostic and treatment modalities. The basic principles behind the production of monoclonal antibodies and discussion of the present and future applications of monoclonal antibody therapy in emergency medicine will be reviewed.