Anti-CD20 monoclonal antibodies are currently used for non-Hodgkin's lymphoma treatment and Rituximab (MabThera) and ibritumomab-tiuxetan (Zevalin) currently approved for clinical use. Rituximab has improved survival of patients with follicular and diffuse large B cells lymphoma. Rituximab is safe with uncommon side effects mainly observed during the first infusion. It is basically used associated with chemotherapy every three weeks and also as maintenance therapy for relapsed follicular lymphoma. A better understand of its mechanisms of action has allowed to develop new generation of monoclonal antibody currently tested in clinical trials.