The development of immunosuppressants with minimal adverse and nephrotoxic effects is important to improve outcomes, such as acute and chronic antibody-mediated rejection, after organ transplantation. In addition, the application of expanded criteria for donors and transplantation in immunized patients necessitates the development of new therapies. Drug development over the past 10 years has generally been disappointing, but several new promising compounds have been or are being developed to prevent acute and chronic transplant rejection. In this Review, we report on several compounds that have been developed to remove allogenic T cells and/or to inhibit T-cell activation. We also discuss compounds that interfere with antibody-mediated rejection.