The development of immunotherapies for multiple. myeloma is critical to provide new treatment Strategies to combat drug resistance. We report a bispecific antibody against B cell maturation antigen (BiFab-BCMA), which potently and specifically redirects 1 cells to lyse malignant multiple myeloma cells. BiFab-BCMA lysed target BCMA-positive cell lilies up to more potently than a CS1-targeting bispecific Antibody (BiFab-CS1) developed in an analogous fashion, Further, BiFab-BCMA robustly activated T cells in vitro and mediated rapid tumor regression in an orthotopic:xenograft model of multiple myeloma.. The in vitro :and in vivo activities of BiPab-BCMA are comparable to those of anti-BCMA chimeric antigen receptor T cell therapy CAR-T-BCMA), for which two clinical trials have recently:been initiated. A BCMA-targeted bispecific antibody presents a promising treatment option for multiple myeloma.