Bispecific antibodies recognizing two different antigens present on different cells have been developed for cellular cancer therapy in which cytotoxic effector cells are recruited to tumor cells. Initial studies with bispecific antibodies have not reached satisfactory clinical endpoints, mainly due to low efficacy, Fc-mediated side effects and immunogenicity. This has resulted in a declining interest in bispecific antibodies for cancer therapy. However, growing knowledge in effector cell biology and the implementation of antibody engineering technologies has led to a revival and the development of novel or improved strategies. Various recombinant bispecific antibodies have demonstrated efficacy in vitro andin vivo, with the first recombinant antibody molecule currently in clinical trials for the treatment of B-cell malignancies.