Radioimmunotherapy is an established and effective treatment in B-cell non-Hodgkin lymphoma (NHL). Currently, two radioimmunoconjugates (RICs) are approved for clinical use in the United States, ibritumomab tiuxetan and tositumomab. Both agents target the CD20 antigen on B-cell lymphoma cells. Although there are differences between these two agents, such as different murine monoclonal antibodies, radioisotopes, and dosimetry techniques, they share similar toxicity and efficacy profiles. These anti-CD20 RICs are active in patients who are refractory to single-agent rituximab, documenting the added value of the conjugated radioisotope. This review focuses on the current use of these agents in the treatment of previously untreated indolent NHL and relapsed/refractory and transformed NHL.