Experimental animal models have made it possible to study some of the biological, biochemical, and pharmacological parameters involved in the use of radiolabeled monoclonal antibody for therapy and detection. Although such models are less appropriate for studies of dosimetry and the host's immune response to the monoclonal antibody, some general principles have been derived from the various model systems that have largely held true in studies in patients. Some of the points learned from experimental animal models will be illustrated in this paper.