The present invention is directed to a combination therapy involving a type II anti-CD20 antibody and a proteasome inhibitor for the treatment of a patient suffering from cancer, particularly a CD20-expressing cancer. An aspect of the invention is a composition comprising a type II anti-CD20 antibody and a proteasome inhibitor. Another aspect of the invention is a kit comprising a type II anti-CD20 antibody and a proteasome inhibitor. Yet another aspect of the invention is a method for the treatment of a patient suffering from cancer comprising co-administering, to a patient in need of such treatment, a type II anti-CD20 antibody and a proteasome inhibitor.