Treatment outcome of malignant lymphomas has been improved since molecular targeted drugs including rituximab became clinically available. However, treatment for relapsed or refractory lymphoma has not been fully established. As second-line therapy for patients with relapsed/refractory follicular lymphoma or diffuse large B cell lymphoma, chemotherapy including alkylating agents or purine analogues, high-dose chemotherapy followed by autologous stem cell transplantation (SCT), and allogeneic SCT are usually selected. Recently, we can also select new therapies including new anti-CD20 monoclonal antibody (MoAb)(IMMU-106(hA20)), anti-CD22 MoAb (epratuzumab), and radioimmunotherapy including Y-90 ibritumomab and I-131 tositumomab.