Research in transplantation focuses on minimizing immunosuppression to decrease side effects and costs. Indeed, in some patients, partial or complete cessation of immunosuppression is successful, but currently we have no means of identifying suitable patients a priori. Current withdrawal protocols, which do not implement surrogate markers, carry a significant risk of graft injury. To minimize the risk, immune monitoring strategies are required. Here, we review recently described biomarkers and assays, which might enable identification of patients suitable for partial or complete weaning and patients at risk of rejection. The predictive power of these parameters has to be tested in prospective multicenter trials.