This promises to be an era of remarkable change for patients afflicted with NHL. Although the cause of NHL remains unknown, there is greater understanding of 'these diseases' at the molecular level. Insights into genetic aberrations that interrupt apoptosis or that promote proliferation have profound implications for the future management of NHL (and other malignancies). Ongoing trials of immunotherapy and RIT continue to show excellent response rates in patients with relapsed or refractory NHL and remarkably favorable safety and toxicity profiles. More drug approvals can be anticipated. As antibody engineering progresses, formerly theoretical questions regarding optimized targeting and antibody affinity, take on relevance and practicality [65]. The ability to generate new constructs, such as bivalent antibodies, or fusion proteins incorporating two disparate functional proteins, presents exciting opportunities for radiopharmaceutical development. The role of bifunctional antibodies in tumor targeting is likely to increase in importance, both as a means of targeting, and as a technique for increasing MAb specificity [66,67]. Pretargeting approaches are in development as a way of decreasing the amount of time that the radionuclide circulates in the blood (radiating normal tissues) thereby allowing the administration of higher doses of radionuclide (radioactivity and radiation) [67-69].