Since the early 1960s, a number of new immunosuppressive agents have been introduced to clinical transplantation. This review will be confined to mechanism of actions, and important gains and concerns of new microemulsion formulation of cyclosporine A (Neoral), mycophenolate mofetil (MMF), FK506, brequinar sodium, sirolimus (rapamycin), leflunomide, and 15-deoxyspergualin. We will also review some of the recent studies with monoclonal antibodies.