Several advances made during the past year will probably facilitate the development of therapeutic antibodies. Most notably, significant progress has been made in the rapid isolation of high affinity human antibodies from phage display libraries and by immunization of transgenic mice. The therapeutic potential of bispecific antibody fragments and Fc-containing proteins has been greatly enhanced by improved production methods. The utility of radiolabeled antibody fragments has been improved by the development of site-specific labeling methods and by the advent of the 'minibody', an engineered fragment that has proved to be highly successful for tumor imaging in mice.