Radioimmunotherapy is a systematic radiotherapy that consists of linking a radioactive isotope to an antibody. Y-90-Ibritumomab tiuxetan is indicated for the treatment of adult patients with follicular NHL with B CD20+ cells in relapse or refractory to rituximab. The Yttrium-90 isotope, a pure beta emitter; provides the capacity for destroying target and neighboring cells. The treatment pattern includes two pre-doses of 250 mg/m(2) rituximab, days 1 and 8 , the same day as ibritumomab tiuxetan and previously. Results: In terms of efficacy, the treatment with Y90-Ibritumomab has shown a higher response rate tan that of rituximab, but without observing any survival increase. This treatment also allows for rescuing a percentage previously treated with rituximab and provides greater safety. The most relevant adverse effect after therapy with Y90-Ibritumomab is transitory and reversible hematologic toxicity. This is a multidisciplinary therapy that encompasses Pharmacy, Oncohematology, Radiopharmacy and Nuclear Medicine.