Dendritic cells, the most effective antigen-presenting cells for priming naive T cells and initiating immune responses, are also able to induce tolerance. This balance between immunity and tolerance depends on the functional stage of dendritic cells (DC). Activation of naive T cells by immature DC can induce tolerance. It is therefore of interest to summarize the effects of immunosuppressive agents on DC maturation and functions. In contrast to glucocorticosteroids, mycophenolate mofetil, and vitamin D(3) analogs, calcineurin inhibitors do not seem to inhibit DC maturation in in vitro culture systems. However, these molecules all appear to interfere with DC functions.