Michael J Burdick, Roger M MacklisDepartment of Radiation Oncology, Taussig Cancer Center and Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USAAbstract: Targeted radioimmunotherapy in non-Hodgkin’s B-cell lymphoma (NHL) offers an efficacious therapy and minimal toxicity compared to conventional chemotherapy. Iodine 131 tositumomab (131I-TST) is a murine monoclonal antibody against the CD20 cell surface protein and is directly covalently conjugated to 131I, a radioactive β and γ emitter. While initially approved for use in relapsed, refractory, or transformed low grade B-cell NHL, investigational uses with promising results include autologous stem cell transplant, intermediate grade NHL, and the frontline management of indolent NHL. This review summarizes the 131I-TST literature on mechanism of action, treatment indications, treatment delivery, efficacy, investigational uses, and future prospects.Keywords: tositumomab, radioimmunotherapy, non-Hodgkin’s lymphoma, Bexxa