Directed against the CD20 antigen on B lymphocytes, rituximab (MabThera) is now incorporated in the first line therapy of symptomatic follicular as well as diffuse large B cell non-Hodgkin's lymphoma and offers superior response and survival rates. 90Y ibritumomab tiuxetan (Zevalin) combines the specificity of rituximab for the CD20 antigen and the therapeutic effect of beta irradiation. Given in monotherapy, it constitutes an interesting alternative therapy for follicular lymphomas in second relapse. Alemtuzumab (MabCampath) recognizes the CD52 antigen and offers encouraging results in chronic lymphocytic leukemia resistant to classical chemotherapy.