Studies in radiation oncology are focusing on the optimal use of systemic targeted radionuclide therapy (STaRT) in the treatment of patients with cancer. The two approved radioimmunotherapy agents, yttrium-90 ibritumomab tiuxetan and iodine-131 tositumomab, are being studied in a range of lymphoid malignancies, from low-grade to aggressive B-cell non-Hodgkin's lymphomas. Studies of standard- and escalated-dose radioimmunotherapy with or without stem cell support are reviewed, as are radioimmunotherapy with other therapeutic modalities in these settings. The results of these trials have important implications for clinical practice, and it is hoped that they will further clarify the optimal timing and dosing of these agents. © 2006 Elsevier Inc. All rights reserved.