Antilymphocyte therapies are widely used for immunosuppression in solid organ transplantation. These agents have varied mechanisms of action, with resulting differences in the intensity and duration of immunosuppression and in associated infectious complications. Induction therapy with antithymocyte globulins is associated with a greater incidence of cytomegalovirus, Epstein-Barr virus, and BK polyomavirus infections, compared with therapy with interleukin (IL)-2a receptor antagonists. However, long-term experience with the IL-2a receptor antagonists is lacking. By contrast, the treatment of graft rejection with T cell-depleting antibodies is associated with an increased risk of opportunistic infections. This is likely a reflection of the intensification of immunosuppression in the treatment of graft rejection and, often, a failure to link the use of antilymphocyte agents to prophylaxis for infection. The use of T cell-depleting agents, especially in the treatment of acute graft rejection, must be linked to monitoring and risk-adjusted prophylaxis for Pneumocystis, other fungi, Epstein-Barr virus, BK polyomavirus, and cytomegalovirus infection.