Radioimmunotherapy (RIT) has been proven effective in the treatment of radiosensitive non-Hodgkin lymphoma but, for radioresistant solid tumors, new approaches are necessary to improve the clinical effectiveness. A real improvement has been the introduction of the pretargeting technology which appeared to be able to significantly increase tumor-to-normal organ uptake ratios.Another very promising approach consists in associating RIT with other treatment modalities. Finally the use of alpha particle-emitting radionuclides such as astatin-211 or bismuth-213 (alpha-RIT) should allow to efficiently eradicate disseminated microscopic clusters of tumor cells or isolated tumor cells which fit well with the short path length of alpha particles.