Low-grade lymphomas pose a considerable therapeutic problem, as they yield to treatment very reluctantly. Not infrequently we are faced with resistance to chemotherapy. This type of lymphomas are usually seen in persons of middle or advanced age, rarely in people under 30. Due to the presence of CD20+ receptor on cell membranes of lymphoma originating from B-cells, monoclonal antibody anti-CD20+ (rituximab) has been introduced to the therapy. This has certainly resulted in improved outcomes. Of value in consolidation treatment of low-grade lymphomas is also autologous or allogenic hematopoietic cell transplantation (autoHSCT, alloHSCT). As escalation of dose of cytostatics as myeloablative treatment prior to autoHSCT or alloHSCT may not guarantee total eradication of residual lymphoma cells, research focuses on treatment modalities which might improve late outcomes in this tumor type. In this setting useful proved radioimmunotherapy with 90Y-ibritumomab tiuxetan (Zevalin). Zevalin combined with high-dose chemotherapy can be used now as a component of myeloablative treatment prior to autoHSCT. Reduced intensity conditioning (RIC) contributes to reduced mortality associated with standard conditioning protocol administered prior to transplantation, but may facilitate disease recurrence. Radioimmunotherapy using ibritumomab may reduce recurrence rate and, as a conditioning measure, may be initiated on the outpatient setting, prior to admission to bone marrow transplantation center. Labeling of antibodies and their application must take place at a Nuclear Medicine Unit, observing all necessary precautions and regulations concerning radiation protection. Administration of ibritumomab is preceded by application of two doses of rituximab: 250 mg/m², 7 days and 4 hours prior to the RIT procedure. The dose of rituximab administered one week before, according to recommended protocol of ibritumomab use, initially preceded dosimetry (administration of indium-labeled antibodies).