Antilymphocyte antibodies have been used for the prevention or treatment of acute rejection in kidney transplant recipients since the 1960s. Both monoclonal and polyclonal agents now are available and generally are classified as either lymphocyte-depleting or nondepleting agents. Use of such antibodies for induction therapy in the immediate postoperative period has varied over the years. Currently, induction antibodies are administered to more than 70% of kidney transplant recipients in the United States. However, the choice of specific agents and the patients for whom they are used vary substantially between and within transplant centers. Many centers use antibody induction therapy only in patients perceived to be at high risk of acute rejection or delayed graft function. Recently, induction antibody therapy also has become the standard of practice in protocols designed to facilitate minimization of such maintenance immunosuppressive drugs as corticosteroids or calcineurin inhibitors. The benefits of induction therapy, including a decreased incidence and delayed onset of acute rejection, must be balanced against the considerable cost and side effects of the individual agents, including risk of infection. Some, but not all, antibodies are associated with increased risk of posttransplantation lymphoproliferative disease and other malignancies.