Imurel and glucocorticosteroid were long the only effective immunosuppressive agents used in prevention of renal allograft rejection. In the 80s, the discovery of a macrolide, cyclosporine A, led to considerable improvement in survival of transplants (around 10 to 20%). Imurel, corticosteroid and cyclosporine constitute the reference immunosuppressive treatment. The mode of use is not fixed and depends on the usage in each transplantation centre. The numerous side effects of these agents sometimes limit their use and, for some, can lead to stopping treatment. Close regular follow-up is required to ensure optimum efficacy and minimum toxicity. Present research in post-transplantation treatment is testing new molecules with powerful immunosuppressive activity, i.e., FK506, rapamycine, mycophenolic acid, sodium brequinar and 15 deoxyspergualine. Some act like Imurel (brequinar, mycophenolic acid), while FK506 and rapamycine have a mechanism of actions that are related to those of cyclosporine A. 15 deoxyspergualine has a different mechanism. The use of these agents in the near future, in association, will allow reducing the nontoxic levels of dosages of each, while maintaining an effective immunosuppression threshold.